My VMware Fusion linux image has the option to use full retina resolution which doesn't work well yet because linux isn't really up to par on dpi scaling, but it also has the option to use the faux resolution 1280x800 (or whatever it is) which comes out looking a little blurry but okay to me.
If you still have your ultrabook you can look at this image at it's normal resolution (not scaled by the browser) and see what the blur looks like http://i.imgur.com/QDdoWNM.png
Oh as an aside i was trying to use Lubuntu (LXDE).
If you're getting rmbp, I would go with the 15 in model. 13 in only uses integrated graphic which has trouble handling the high resolution.
Either that or it is something I don't run into. I don't play games really but I haven't noticed any frame lag when scrolling.
In Linux I live in tmux + emacs + i3 + browser, and they can easily be configured with larger fonts etc.
I would love to move to a quality display with resolution > 2560x1440 to get crispier fonts (although many other aspects of a display are just as important as resolution).