I am no master horticulturist, but I've tried all 3 techniques, and I will share my experiences of them.
Low Stress Training (LST)
Pros: -Definitely increases your yield. Instead of one large cola bud, you get lots of smaller popcorn buds. The final result is quite a significant increase in yield.
-Controls height of plants, allowing you to have a more compact garden, and an even canopy.
Cons: -Can be very time consuming, especially if you are growing more than a couple plants.
-In my experience, the string attached to the side of the pots really get in the way of just about everything. The annoyance of the strings was not something I planned for. Having those strings in my way on all my plants is actually what swore me off of LSTing.
-On short growing strains you really need to veg longer than normal or you will see diminished yields as opposed to increased yields.
Summary: LST is a great way to increase your yield if you have only a couple plants. If you have more than a few plants it becomes a very time consuming process, and your lower garden will become a jungle of twine and string. If you have one or two plants, LST them, if you have a full garden IMO other methods are a better option.
Fuck I Missed It (FIM'ing)
Pros: -Will definitely increase your yield. Instead of one main cola you will have multiple.
-It's very quick to do. Takes 2 minutes per plant instead of 20 with LST'ing.
-The recovery time for your plants is supposed to be much quicker as opposed to topping (Although 80% of my topped plants have recovered in 24-48hrs).
-Will help slightly with the height of your plants, but not as much as LST or topping.
-You can FIM a plant more than once while it's vegging (I believe, haven't personally done it twice to the same plant.)
Cons -The amount of colas that come out of the FIMMed area is totally random. I've gotten 4 colas, I've gotten 2 colas, I think its just the luck of the draw really.
-Does not combat height like LST or Topping
Summary: I have been FIM'ing my short growing plants that don't react well to topping, and they react really well to the FIM. You may not get as much yield as you would LST'ing (you may though, depends. The number of colas that grow is random.), but it will take you only a fraction of the time. This is a feasible option for large scale growing, while LST is not.
Topping (Uncle Ben's Topping Method)
Pros: -Greatly increase your yield, by getting four colas every time.
-Unlike FIM'ing you know what you're going to get 100% of the time, 4-colas.
-Helps to control height, and allows you to create an even canopy.
-Each plant you top gives you a clone. Even if the nodes are close together so the cutting is very short, plant it and it will live.
Cons: -Will stunt your plant for a day or two.
-I don't know if this was grower error or if it just happens, but in my experience about 20% of the plants regardless of strain will be 'super stunted'. It takes these plants about a week to bounce back as opposed to 1-2days. So 20% of my crop is 5 days behind the other 80%. Not really a big deal in the grand scheme of things
-One of the four colas may be the dominate cola requiring you to tie it down so the others can catch up.
Summary: Personally I think this is my favorite of the 3. That may change because I just did this to my entire crop for my first time recently. I haven't seen the effect on final yield except in pictures. But so far it looks like its working perfectly, 100% of my plants have 4 colas. And being able to get 1 clone per plant so early in it's life is awesome, especially for a perpetual harvest.
So those are my opinions and experiences. Hopefully it helps someone.