HGU/55 shell (best headroom clearance, more flexability regarding visors), Oregon Aero liners and earcups, and CEP in-ear passive noise attenuation.
I know the ATPLs I fly aeros with tend to prefer the Alpha Eagle, as it arguably provides better impact protection and even a few percent is significant if it reduces your chances of being on the bench for months following a concussion, but if headroom is a factor then the Alpha may be too bulky.
I've never found the weight to be an issue - when I get home I'll stick the Gentex and a pair of DCs plus cloth helmet on some scales and post the respective weights.