I'm trying a good balance and comprise for my next iMac. Photography editing (RAW files of a D800 and soon an X-Pro 1) is my main hobby, followed by iTunes (music listening and streaming content to my Apple TV), and finally a bit of gaming (Starcraft 2 and Diablo 3 and Portal 2, mostly). I may boot camp to Windows for some other games, but I'm not TOO big of a gamer like I used to be. The iMac's I'm looking at are the same in CPU, RAM, and Fusion Drive, but the difference is the GPU (650M on the 21.5, and 660M on the 27). There's an $80 difference in the two. Is the 660M worth the extra $80. Also, I prefer the 21.5 size, but wouldn't mind the 27 if it's worth the 660M GPU. Thoughts?