I know what a SCROG set up is. What i do lack in experience i do have in knowledge.
Knowing is one thing, but actually getting it done in the real world, something else.
I'm also transplanting from a solo cup- to a 3 gallon, to a 5 gallon, to a 7 gallon, hence a bigger root mass and ideally more fruits
IMO, that's at least one, and (depending on space contraints) possibly two more transplants than you need.
More transplants = more shock to plant = LESS yield in the same time period.
Your concept of moving up into a large final pot is good, but what does the 5 gallon pot buy you here? I don't see why you need more than a cup to germ your se-ed, a small pot for sexing, then your final pot.
Also, and more to the point, yes with any given individual plant more root volume CAN lead to more weight, but that's only true if root volume is the limiting factor. Typically that's NOT the case in indoor growing. Once you know what you're doing, the biggest limiting factors indoors are almost always watts and available space. Again, a larger number of smaller plants typically outperform a smaller number of larger plants. Its more about making sure no light gets wasted and filling up all available canopy space than pot size.
And don't forget it's not about how much wattage a light uses, it's the lumens.
Well, in fact, lumens are meant to normalize lighting for human eyesight. Since most of that spectrum lighting doesn't grow plants, lumens aren't actually a very good way to compare between different types of lighting for growing. EG, you can have high lumen output bulbs that aren't very good at growing plants because of poor spectrum (eg halogen incandescents), and vice versa, lights that are good at growing plants, but not so good for reading a newspaper (eg specialty LED grow lights). The best way to normalize between different types of lighting for plant growth is to compare "PAR", photosynthetically active radiation, or "PUR" photosynthetically useful radiation, not lumens.
Regardless, as a matter of practice, virtually all pro growers use one of two different lighting systems for flowering plants: a. Sunlight, or b. HPS. Since all HPS lights put out roughly the same spectrum, if you're comparing them, there is no functional difference whatever between lumens, PAR, PUR, or watts. With a few minor caveats, all four of these things are going to be directly proportionate to each other. So yeah. . .it *IS* about watts.