Went in today to have a look - retina screen worked as I had expected with the 27" display. Shame the 13" doesn't share the same resolution of 2560x1440 (it's 2560x1600).
Bottled it with any purchasing today. I'm not convinced about the 13" i7 over the 15" 2.7GHz i7...I gave both a good run today at typical things I do, and there was no obvious difference between the two at all. I'm not sure I utilise the quad-core i7, but at the same time I know the quad-core has me covered. I think the laptop everyone is waiting for is the 13" with quad-core!
Either way, I'll wait a few weeks for the new 27" Cinema display! Thanks for everyone's help/advice