I tried CM 7.2 (Mirage), CM9 (nightly build was only that I could find), CM10 (Schizoid), and CM10.2.
Only CM 7.2 was fluid. There's some hiccups but it works. The on screen keys are annoying and small, but it's def a miracle they're there at all.
I was not able to try CM11 as the latest TWRP & CWM recovery builds posted (
http://xdaforums.com/nook-color/dev...-0-5-1-unofficial-t3000062/page2#post67733949) are lost with their link. The CM11 page said "faster than CM7" and Kitkat could - but I was not able to confirm. If anyone has access to a newer TWRP/CWM than the one posted by eyeballer, lemme know.
To get my Google Account activated on CM7.2 I had to use a device-specific password. It said wrong PW otherwise, even though it was def right.
Edit: Looks like Gingerbread is too old at this point. The Playstore had major issues and many apps refused to connect at all - despite installing. I managed to get to CM11 which is faster than the others (CM9/10) but not as fluid as CM7.2.