If I were to buy the more expensive macbook pro 15" (the one with nvidia 750m 2Gb), would i be able to play most games (through bootcamp) without problems? For example GTA 4 (and 5) and other.
The state of 3D gaming on Mac's is a sad one.
Yes you can play the current 3D games on that top end model of Mac, however Apple doesn't put awesomely powerful graphics in their laptops to better survive the newer games released.
After about 1 year or 2, your top end Mac laptop is near obsolete.
Apple has been gravitating away from powerful graphics in their portable Mac models over the last few revisions, in fact now only the top end 15" has heavy duty graphics, when all the 15" before did. Sure the Intel CPU graphics has increased, but not enough to replace dedicated graphics.
New models are also coming sealed up, so you can't clean them of dust that gaming accumulates.
So since Apple is signaling the end of 3D gaming on it's laptops, your better served on a PC.
I suggest you look at the Sager Notebook line, they can come with DUAL videocards, multiple RAID SSD's and up to 32GB of RAM, plus the ability to clean the dust out.
Since they come with Windows, that's one thing you won't have to buy like you would if running Apple's BootCamp to run Windows that way.
No problems with updating drivers or system tweaks neither, which is a problem on Mac's.