I have an m4forgery (BCM 14.5"/perm A2X) with a Troy rear folding sight and standard (F-marked) FSB and want to mount an Aimpoint T-1. I would like the T-1 to co-witness (not bottom 1/3rd) with the irons and am wondering which mount will do this for me. If this is not possible what mount will co-wit a comp m3 with this irons setup? Also, 2 MOA or 4 MOA on the comp m3? Thanks in advance! 
I do not believe Larue makes a mount which will allow absolute co-witness with irons for your Micro T-1. The LT-660HK (meant for HK-416 and piston uppers) will bring the sight down lower on your rail, but will not provide absolute cowitness.
Again, Larue does not make a CompM3 mount which provides absolute cowitness. The closest thing is the LT-152 mount which is meant to be mounted on the hump of the KAC RAS II.
I would definitely recommend the 2 MOA dot on the CompM3. Much crisper and you can achieve close to 4 MOA when turned on to the highest setting with bloom.