I have the 10mm, it's an interesting gun. The only real issue I have had is with magazines, mine does not play well the pre-bans as they wouldn't lock in reliably, newer ten rounders worked fine. What I ended up doing is removing some of the material on the base plates and they all locked in ok after that. I meant to explore the issue further but never did, could be a bad mag catch or maybe the receiver is over molded? I got it working so I left it there.
The other issue was the mag release snapped in half one day at the range, it's MIM part so maybe it was just a bad one, who knows. It was easy enough to replace and since then I haven't had any other issues, granted I haven't pushed tons of lead thru it since then.
I put a C-More sight on mine and put an ACE entry stock on it at first, I switched the ACE out with a Magpul fixed carbine stock