Here's something I'm wondering:

If GSP beats Penn, moves to to face Silva for the title and beats him, will he defend both the 185and 170 lb belts, or will he stick to one weight class?

Moving up and down from 155-170 wouldnt take that much of a toll on the body, would it?

Now moving back and forth from 185-170 may be a different story because I'm sure GSP plans on bulking up significantly for a 185 lb fight.