My experiences with my Sub9 have also been very positive. It has been a very fun little carbine for me to own and shoot.
The Sub 2000 is still too new for a real thourough background on it yet, but for the most part it is very close to the original Sub9 except for the polymer reciever.
Considering Kel-Tec's excelent reputation for "making it right" quickly and efficiently, I'd take a chance on one if I didn't allready own my Sub9.
Andrew