I just purchased a 27" 3.4GHz i5 GTX 775M iMac. Awesome so far. I will add an external SSD at some point and use that as the boot drive.
Does anyone have any experience with gaming using the 775M?
It about on par with the 680mx from late 2012 iMac. I think the 680 inches it out, but the 780 beats the 680.