I personally like Aimpoints. I've owned both the Eotech 510 and 552. I just never really liked either one. I prefer the single red dot over the holographic picture. Currently I have the M4, T-1 and ML3. All over them are awesome, but I think I like the T-1 most. Right now I'm using it on my XCR with a Larue 416 mount. Its super quick to get on target, and I can hit steel plates at over 200 yards with no problem. I don't feel like the 4 moa dot size is too big at all. In fact, it doesn't seem that big to me.
As far as the Comp M4, I'm using it on my LWRC. I do like it a lot, but it is a little heavy. I'm thinking of replacing it with another Micro T-1. IMO the T-1 is by far the best red dot on the market right now. Take a look at one if you get a chance.