Bluetooth issues on a tablet are a problem, but on a phone they'd be a deal killer.
My 15 mos. old rooted HTC DI2 running ICS have no issues with Bluetooth, including Skype (soon to replace MSN Messenger, arrrrhhhh) and Google Voice or GrooVe IP when calling, crystal clear. N7 running 4.1.2 on rooted stock rom & kernel is fine, Bluetooth is fine but "playing" now with 4.2.1 - BT is a P I T A - no matter how I try to tweak it, whether I'm using the Jabra or 1 of the 2 Moto headset.
Benchmark-wise, not that I am chasing for a high Quadrant score as the CPU/device is plentiful fast for my purposes without OC/UV - 4.1.2 has clearly the upper hand, whether it's stock rom & kernel or custom rom/factory kernl or stock rom/custom kernel.
Fortunately, Stickmount is working on 4.1.2 with my choice of roms at the moment, MoDaCo's Jr13 with franco - and, it's a "messy" one with the sdcard directory layout for the recovery whereas with 4.1.2 - everything on it is easily accessible for backup & restoring with CWM.
Just my 2 cents, as a disclaimer - YMMV - of course.