GTX 675MX or GT 755M? 27" iMac refurbs

I'm looking at picking up a refurbished 27 iMac. I wish my pockets were deep enough to spring for an i7, but I'll have to settle for the i5.

I see late 2013 models with the GT 755M video card, and late 2012 models with the GTX 675MX video card, both with 1 gig of VRAM. Every single source I've looked up has stated that the GTX 675MX is actually quicker than the 755M. Is this correct?

I'm mainly concerned because I do a moderate amount of gaming, and the occasional video editing with Adobe Premiere. I'm pretty sure both cards can be utilized by Premiere's Mercury engine, but of the two, which would help me speed up my render times?

I'm not overly concerned with the Ivy Bridge vs Haswell situation, but I wouldn't mind the updated wifi speeds with the newer 2013 model.

Any thoughts or suggestions are very appreciated.