I bought a U-binned Groovy! with my name on it some time ago.
It's a nice light and I find the output to be very good but PhotonFanatic said that it was a Luxeon lottery winner so it might not apply to all of them, as always.
The knoll switch did break for me two weeks ago and I haven't been able to fix it. I've heard reports of the knoll switch malfunctioning and mine wasn't completely centered either, but otherwise it's fine.
I don't know if he has any of the other versions for sale. One of them looked like it was sandblastered. It looked awesome!