BJ's got a great chin and other than gassing out against Hughes, has never been stopped. However, you can basically say the same for GSP, except for the chin, which was exposed by Serra.
I thought BJ won the first fight. All GSP could do was take BJ down, which didn't really score points for me because of BJ's BJJ pedigree. BJ had GSP's face bloodied up half way through the first. That was years ago, and GSP has looked awesome lately. However the KO from Serra and the resulting psychiatry sessions make me think BJ has the mental edge in this fight.
I think BJ will keep it standing as long as he can and use his boxing to frustrate and soften up GSP.
There is no doubt it's going to be a great fight. BJ will be in shape. At this point, a mega fight is the only thing that can motivate BJ to be in tip top shape. I can't wait to see it.
If it kills, I got news, it ain't a side effect