how does the gt755m stack up against the gtx775m? is the latter significantly more future proof than the former? i'm a moderate gamer, but my imac doesn't need to a gaming machine, it just needs to last me 4 to 5-6 years. if i go with the gtx775m & 1tb fusion drive, the cost would be pretty much the same as when i'd go with a gt750m & 3tb fusion drive. storage is a factor, but now with usb3 on board not so much. i'm not really looking for benchmarks. also, how useful is the trackpad with a 27" imac? i love the trackpad with my mbp, but i have no idea what it would add to the imac experience? thanx!