Hmmm. I got my new KT4-SR up and running two days ago (swapped out from a MSI 266a) and I'm loving this board.
Got the new new board with my locked 1600+ AGOIA Y running nice and stable at 1780 MHz (169 fsb), and I haven't even pushed it yet - I'm certain it will easily go further. Been running Fold@home for a day and a half at this clock with no problems or errors.
With the SLK-800, my temps are right around 41c at this speed under a full load. My only complaint is the ThermalTake smart fan II is a bit louder than my old setup (at full speed), but that's expected for pushing 76cfm. I plan on drilling my case so I can run the lead to the fan externally so I can quiet it down a bit the majority of the time.
Anyway, without one crash at this clock speed, and taking into consideration I never even formatted my hard drive from the 266a, I'd have a hard time calling this board a 'beta'. The serial RAID will probably also be a good feature to have when it becomes more available.
Anyway, here's a vote from someone who's been very happy with the performace of this board thus far.