Cool, good to hear, I've actually started playing with Carbon ROM (hence why I made this post, but figured I'd try it first hand as well).
But yea, I haven't found any bugginess so far, although I haven't tried GPS or MMS yet, will have to do that..
And yes, I am aware I'm off OTA path. 232 was the last (or close to last) leak that could go back to GB moto base, so I stayed here.
Flashing back to GB has helped in getting my old MAC address back after flashing ICS ROMs. If JB kexec on ICS base works out well enough, I'd still consider no reason for me to move ;P
BTW, you mention new features on the JB upgrade.. the new features are only apparent inside the stock ROM, correct? I wouldn't think I'd be missing out on any features if I'm not running stock ROM, but I've been wrong before