How about a 17" early 2011 MBP? I haven't done much gaming on it other than native Starcraft 2 and it always seemed like it made the whole keyboard area really hot. I've been told that's normal, but I still worry. I notice running Windows 7 on boot camp, just running windows alone doing general stuff, gets it heated up a lot more than the mac side.
I have a 17" with the slower processor, but it didn't seem to be that big of a difference between the 2.. and I upgraded to 8 GB of Ram.
It'll run fine.
6750M is considerably more powerful than the XBox GPU.