I've run Cyanogen 7.1 stable on my Cappy since it came out in October, and with exception to horrendous battery life, has been great. I was having a lot of problems with the official 2.2, usually requiring a daily reboot and more than my fair share of battery pulls. It would connect with my car's bluetooth (Dodge Charger) about 1 in 3 times.
Since rooting and mod-ing to Cyanogen, the same phone is stable, always connects to the car, rarely any problems (currently over a week since last reboot), and as a bonus, can be used as a mobile wi-fi hotspot so I can use my data plan on my laptop and tablet at no costs and no cables. The only downside is the battery dies after about 14 hours of no use, but that maybe because I have Touchdown widget pushing my work email to me.