About the weight gaining, it all depends on eating right training right, etc, etc. It can be done, but it extrememly hard and also depends on your body type. Manny was eating, I believe, 8000-9000 calories a day while training for Cotto, just to maintain his size! If, and when BJ moves up, he won't beat GSP (if GSP isn't up to MW by then). I see him having excellent fights with guys like kos, alves, fitch and being on par with them. GSP will just do to him what he has done to those guys (IMO)