Got my 512 on Monday thanks to the prompt service of the fine folks at CMMG Inc.
Zeroed on Tuesday at Carter's Country. I am now in awe of my carbine.
I love my Bushie M4gery, but it has been impossible for me to be TRULY accurate with the ghost ring sights. I was totally underwhelmed with my ability to group shots with first the A2 sights and then the ARMS #40 (I had KKF slap on an A3 upper while he was installing my A3 Tacbrake). It used to be a good trip if I could keep all my shots within the 8 ring at 100 yds. So, I saved money and kept on reading here to help me decide what optics platform I would use.
Looking through both the Aimpoint and EoTech impressed me, but I believed the HWS reticle would be capable of more accuracy due to the 1MOA dot, and I preferred the low-profile look of the EoTech. I finally let SMGLee and others convince me (indirectly) to give it a try. I am very glad I did. I decided on the AA version for the ease of getting batteries, even though it has to sit a bit more rearward than I'd like. I was able to shoot so much faster and more accurately that I was utterly stunned, it was like shooting a whole new rifle. Anyone still opposed to red-dot optics has no idea what they are missing. The AR series did not truly come into its own until optics like these arrived on the scene, I just don't know how I got along without this thing before. My vote for the EoTech is definitely cast for the forseeable future.
Now to save up for a decent flashlight to replace the Streamlight Scorpion attached to my Fobus M33s (which will fall to an RAS shortly after that).