Don't know how true it is but I read somewhere on TFL, Ar15.com, 1911forum.com or GlockTalk.com, that there was a class action lawsuit involving the Carbon 15 weapons.
It had to do with their reliability and how many trips back to the manufacturer the guns were needing. I would say that if you have one that works, be happy, but I don't have first hand knowledge.
Again, not to start a flame war!