ok - it's been discussed ad-infinitum. Most of us are pretty sure that a 27" retina iMac is not a likely addition to this year's lineup. But, what if they did the same as they did with the MBPro range and added a single retina iMac with a screen that was practical and affordable. How small would you go to get that extra resolution and what would you sacrifice for it? For example would a 17" retina display be tempting? Would you rather have that than a 24" regular resolution? What about a 21" retina versus 27" regular?