On both ROMs I've experienced issues with the unit switching itself off (as incompletely powering off, with even the power light off). I believe I may also have experienced this on the standard ROM, but can't really remember as it was so comparitively unresponsive I only had it on for a matter of a couple of hours.
Having done a little testing with FB7.2 it only occurs when the device is in use and then it's quite variable (can be within 10mins of using can be a couple of hours). My gut feeling is that it's hardware based as the problem has occurred in the 2 ROMs I've tried (albeit to varying degrees); has anybody else experienced any similar problems?
As an aside, apart from the switching off the unit is excellent when combined with FB7.2