So I do a lot of heavy editing which causes my baseline rMBP with the 650m to slow down pretty quick. I'd say right around the 60 second mark my computer starts to choke and can't handle the amount of layering I do. I'd like to upgrade soon, to a new rMBP or possibly an iMac/Air combo. I'm looking at either rMBP - Iris with 16gb ram iMac - Maxed out (21 inch model) Could possibly get a rMBP with 16gb ram and the 750m, but i've heard the Iris Pro tweaked for Open CL does a pretty good job of keeping up on FCPX and Aperture. Was wondering how much more of a performance boost I would see from either going for the higher end rMBP with a video card, or the 21 inch iMac maxed. I've never owned an iMac, besides the bigger screen do desktop parts really increase performance by that much if everything is pretty similar in specs?