With LST you keep it 1 height, you just increase the canopy horizontally. So you can't really say how tall it should be
LST can increase your yield exponentially. Because LST allows light to hit the lower nodes, they grow upright as if they were main nodes. I have some plants that have 10+ bud sites, so compared to a plant that just grows straight and tall with one main node (bud site), I would say I get roughly an 8x increase in production. I know whatyou are saying 'no, that's a 10x increase'. Well, while there may be 10 budsites, they kind of split the energy of the plant and therefore each of them don't produce exactly as much as if you let the plant grow with one main budsite. But, overall you will still yield more because of the multiple bud sites. Hope that makes sense. It did in my head. As for trying to predict your total yield, that is nearly impossible. Just way to many factors involved. Strain, conditions, lighting, etc. Just grow and have fun with it and whatever you yield you yield. Your yields will get better and better with time and practice. Good luck.