I don't know about the M4, but can compare my Wilson AR to my MSAR STG 556, an AUG clone. Both have nominally identical barrel lengths, at 16", +/- flashhider length. With an ACE SOCOM adjustable buttstock with rubber pad, in "normal" light clothing position, the OAL of the AR is 35". The STG is 28", which is a world of difference in handling ease in confined space such as a truck cab, but also the condensed mass of the bullpup makes it easier to handle, and carry in a tactical sling. These rifles haven't been compared with identical optics --- there's a conventional Leupold 1-4x on the AR, with which it shoots sub-MOA without trying very hard, even with Black Hills remanufactured ammo. The STG is fitted with an Aimpoint 2x/2MOA red dot, and with the same ammo, can, with care, hold close to MOA. The STG trigger is not even close to the Wilson's superb JP trigger, even after a little work. I guess I regard the bullpup as well suited for CQB, vehicular, and urban use, and the AR as the more capable GP rifle. I recommend availing yourself of one of each type!
