It is too late to chime in for the decision making process but I will toss in my two cents anyway.
Using small pots equates to a root-bound condition where the roots of your plant outgrow the container they are contained in. Growing in a root-bound condition can cause various problems, the most common ones are stunted growth, which is not the way to control plant size since it is done by stressing the plant. Even with good lighting stretching is common to root-bound plants. A major drawback is slower and lesser bud production. Everyone always wants ‘more’ and never less, and everyone always wants ‘faster’ but never slower, so why create a growing situation that causes those unwanted results? As was mentioned, frequent watering is needed, frequent enough that it is not all that difficult to make an error either way that can cause at least a limited setback. Why risk it? When plants are forced to survive in a root-bound condition even low percentage solutions of ferts/nutes can and will burn plants. Add in the normal amount of human error when mixing ferts/nutes and what would otherwise be a very minor error could turn into a major tragedy. Growing in a root-bound condition you greatly increase your chances for making a significant error. This goes with the frequent watering, and how at times it can fool someone into making a real error, is wilting. When you find yourself in a situation where you know you need to water often it is easy to overcompensate and assume any leaf wilting is a sign of needed moisture when it could be the time that you watered a little extra the previous time and humidity and temperatures had been a tad bit lower than normal and what your plants are telling you is, enough of the water already. No mas, no mas. The more trained growing eye will likely spot the difference between dry leaves and over watered leaves but until someone has developed such an eye they are playing with fire, things can go either way regardless of what you believe is happening and with so little soil with so many roots tightly woven around and all through it to work with, there is little margin for error.
It is not impossible to get yields that would impress a good grower using smallish pots. You just have to be good at using them, at reading plants instantly and accurately. Once someone is experienced enough, once they have it all down pat then they can do well with smallish pots.
For everyone else, bigger is always better. I never use anything less than 5-gallon pots, and often enough I will use 7-gallon pots, and 15-gallon and larger when I used to grow outside on my deck. I do not recommend anything smaller than a 4-gallon pot, ever, for any use/application, unless possibly something is some super midget dwarf strain that only grows about the same size as a Venus Flytrap.
Once a plant’s roots begin to circle the pot they are in the plant is then under a degree of stress. The worse the circling becomes the greater the stress and once it becomes a root-bound condition the stress is maximized.
That is not just marijuana specific information, that is general proven botanical science. The only saving grace marijuana itself possesses for if and when grown in smallish pots is it is a hearty weed, one that is a survivor, one that takes a licking and keeps on ticking … that last one was for all of those in the Viagra Generation.
Because of that growers who are not actually what could rightly be called highly skilled growers can use smallish pots and end up with results that are good enough for them, so they assume they are doing great and continue down the same growing path.
The thing is they just do not realize how much better they could do with the same number of plants, or in some cases even with fewer numbers of plants if they used larger pots. Happy healthy plants produce better than unhappy possibly unhealthy stressed plants produce.
An eyeball rule of thumb is plants have a very close to 50/50 size of area equality between root-mass and above-ground growth. Yes the above and below soil growth is shaped very differently but area of mass is very close to being equal above and below the soil. If you look at a plant and think how crowded the plant would be if you reversed it in its pot, putting the above soil portion in the soil, and think …. no way in Hell could that ever happen ……. the plant is in to small of a pot.
Trimming off lower leaves and or entire branches will not alter the below soil growth significantly, it is genetically coded to grow in a certain way to maximize its ability so the rest of the plant above the soil can carry out its function, to continue to survive so it can produce seeds. Trimming off leaves or entire branches no more stops plant roots from growing than if a storm broke off a large limb or two off a tree in someone’s yard. Every time you cut a portion of a plant off that is not sick/damaged/light starved to the point where it is dying the plant will attempt to replace whatever it is that you cut off. Depending on area of the plant/conditional effects, it might not attempt to regrow what was lost in the same location but it will try to regrow what was lost somewhere. The energy believed to be saved by not going to leaf and or branch growth is not magically or mystically all transformed into energy for bud growth.
The root system will not see the above soil loss in a way that tells it that fewer roots are then needed so it will slow down root growth for a while. The roots will continue to grow expecting the plant to heal itself and regrow what was lost, or at least to attempt to do so as long as the given life expectancy/time-frame allows, so the root system will want to be at its prime for when the plant/bush/tree begins to recoup from its loss. That is just how plants do things.
If you want shorter plants try to pick shorter strains, if possible. If not then consider a growing technique that will keep plants shorter overall. If need be cut back on vegging time or in the case of something predominantly sativa, or all sativa, start out with a 12/12 lighting cycle or follow Uncle Ben’s topping technique and normally end up with three or four main leaders, giving you three to four colas per plant, and plants that are shorter overall even if no other system is used to keep them low, though likely not as low as some growing techniques would keep them … but then you can always combine the best of two worlds and do two or more things that would result in happier healthier more productive plants that remain manageable for all but possibly the smallest of growing situations/areas.
Using pot size to control plant height/size is the worst possible choice to make to attempt to control plant height/size and should only be used as a last resort. At the very least use 4-gallon pots or larger and then do whatever else might be needed, and that would be better options to pick from, if increased unwanted height/size could become a factor.
Something worth considering for anyone who grows in soil/pots is the air root pruning pots that are available. They are not inexpensive but they will create a very healthy fast growing root-ball. Of course adequate pot size still has to be considered but they work well and are worth the investment for anyone who is an all soil grower and will likely remain so for at least a few years or so to come.
For the very few of you who might not be familiar with the pots, they have small air holes around the pots, made in a way so light does not shine in but increased air does get in. When a root tip touches the air it dies and then it splits off into two different directions somewhat similar to topping a plant. Rather than the plant’s roots hitting the sides of the pot and then begin to circle the pot stressing the plant, the roots head off in a more scattered way taking somewhat differing directions each time one splits. That eliminates pot circling by roots and more fully utilizes all of the soil in your pots and that also means increased efficiency in the uptake of moisture and nutrients.
It also means that you have greatly reduced the chances of experiencing the above list of common problems that go hand in hand with growing in smallish pots.
That is just a little bit of experience I have gathered over roughly 39 years of growing and also from being an investor in a family owned nursery, trees and bushes, not snotty nosed smelly diapered kids, that covers around 15 acres of land and is almost 100% a pot-in-pot nursery. Acres of land is covered in a thick black growing cloth and long rows of socket-pots are set into the ground. Each tree or bush begins its life in a smaller sized pot, sometimes only a 1 or 2-gallon pot, and then each year, or more often if needed, they are bumped up a pot size until they are sold at whatever size they happen to have grown to by that time, though of course we always try to have a wide selection of all products in various different sizes at all times to meet the current market needs.
When you deal with thousands and thousands of things growing in pots you tend to learn a thing or two about growing in pots, even in a case like me where I do not normally work there, I only help out now and then if a short-term need arises, but being an investor, and family too, I hear all about the things I do not actually see myself.
Combine that with the very near four decades of experience at my little hobby and I can tell you that I am not blowing smoke up your sphincters. I can also say that anyone who tells you otherwise is blowing smoke up your sphincters, even if they do not realize they are doing it because they mistakenly actually believe that they are correct even when talking about all growers/setups/conditions/levels of skill rather than just those who are very good and who can and will put in all the additional needed time and effort.
Put in short, something I am not well known for attempting to do, unless you are damn good, and I really do mean damn good and not just think you are damn good, always use bigger pots. Heck, even if you are good enough to use smallish pots, regardless of if you care to believe it or not you would actually do better using larger pots so it is still worth you at least considering it.
Aggreed, don't expect much more than a oz in one gal pots....best I ever did in a 1 gal was 2 oz and that was more luck + strain I think. If you can bigger is always better IMHO. But it most def can be done as I have completed many grows in 1 gal air pots......