I had one for a while and liked it a lot. I'd say it's a good "2nd AR". If you're only going to have one AR, I'd make it an all metal one. There are parts on it that are not the same spec as other ARs. I think even changing out the hand guard is a problem.
The redot usually isn't the TRS. It's Bushnell's budget reddot that sells for $50-$60. It was ok, but I've heard much better things about the TRS.
You used to be able to find the Carbon's for under $700. That time is gone though so $800 isn't terrible. I heard that they were extremely popular so there's a bunch out there. I'm hoping they pop up used for under $600 eventually.
