There's a fairly lengthy thread on M4C regarding these bolt carrier groups. I'll say up front I don't own one, and have no personal experience, but many people in the M4C thread have purchased them.

My biggest concern is that they haven't been consistent based on the pictures that owners have been posting over the last 6 months. Some come with coated firing pins, some don't, and at one point they changed their staking method, then back again when people complained (although it doesn't appear that the different method was ineffective, rather it simply didn't look like the nice staking from a MOACKS). Additionally, RCA said they were going to stop using forged gas keys at some point, and switch to CNC'd gas keys.

Food for thought.