well I can tell you I have to eat more using metformin. if im usually feeling energetic, full, ready to go with 35pro/50carb/10fat and then dose metformin 15- 20 min before that meal it will feel more like I ate 30carbs and be hungry for more. I also felt immediately weaker in the gym, for those two reasons alone i stopped using it the same with t3.
The strongest and biggest I ever got I was bulking on 50t3 ed (gearv as well of course). I won't go over 50 cutting though as then the flatness and weakness does start