Been cogitaing some time on new kit. Decided on iMac 27" or mini mac plus thunderbolt screen. Issue is 5K retina or not? Anybody got one? Is it really as good as is claimed? I'm not terribly mobile at the mo, so was a tad annoyed, after a painful shuffle along to my local showroom (PCWorld) to find that they only keep 5K's on display in, "..in our larger stores." Opinions gratefully received. Thanks.