I don't know if it's your culture or what, but you definitely look like an ass regarding your responses in this thread. You stated many times that you searched and didn't find anything regarding "what you were looking for". I am one of those people who reads every little detail about the dGPU's in the rMBP's and I can tell you with much honesty that everything you could possibly want to know about the 650M (2012 rMBP's dGPU), the 750M (late 2013 rMBP's dGPU) and the Iris Pro has been discussed. That is, comparisons between the 650M and 750M, comparisons between the 750M and Iris Pro, and above all significant amounts of information comparing the 650M and Iris Pro. It would appear that you are not searching well enough, or hardly spent the time to look at all.
With all that said, I will answer your question. IMHO the (late) 2013 rMBP is a waste of money (if you care about gaming). The 750M is extremely close (within 10%) in performance from last year's 650M (they are actually the same card), so you are better off saving hundreds of dollars by buying a 2012 model. Both the 650M and 750M will be able to play the majority of games in Medium settings, and a resolution lower than 1080p. Weaker games you can play in High and very weak games (counter strike) you can play in Ultra. Likewise you would only be able to play some games in 1080p if you scale down settings into the low-medium range. Some games this dGPU simply can't handle. Do not expect to play expansive games well at all. Games like battlefield apparently hold up okay, but you will not be able to play strategic games like Rome Total War, or Age of Empire in Medium settings.
It is of my opinion that next years model will be much better in the dGPU department (unless they take out the dGPU from the higher end model as well - which they very well might), because NVIDIA is coming out with new chips this year, instead of just rebranded chips, like the 750M is to the 650M.