I have extensive hands on with all the aimpoints. Hands down the T-1 or H-1 is the way to go for your CQB needs.
The M4s is great but for the price it just doesn't offer anything special to justify.
The M2 and M3 are great for the price and performance across the board.
Though the T-1 and H-1 are very robust, low profile optics that provide a long battery life and perform well in any environment. Unless you need the NOD option just go with the H-1.
I saved some money on a nearly new Comp M4s in the classifieds. It's a great sight, very robust, relatively light and compact. The co-witness in the LaRue mount works perfect. Now that I know what I know I think I would get the H1/T1 instead because it is even more light and compact. I'll probably just keep the M4s simply because I haven't found it worth the trouble to swap out for the H1/T1.
I'm a big fan of the H-1/T-1 as well. You simply can't beat it for compact, lightweight, and high quality. Shop around some of the classifieds I'm sure you'l be able to find one for a good deal.
Free Aimpoint X Wide 30mm Pictinnany Style Ring
Free Aimpoint Bikini Lens Cover
Free Aimpoint Front & Rear Flip-Up Lens Cover
Free Aimpoint Black Outer Rubber Cover
This is a good deal at $399.95. The CompC3 is the same as the CompML3, only difference is the ML3 can go deeper under water for longer and cost $85. more.