For me, it was quite difficult to "catch the train" with ACE, as I wasnt following the mod from the beginning. Just saw more and more servers running it. When I tried to dl it a came across many other addons that needed to be installed as well and it all became messy for me until the SIXlauncher came, but later on the SIXlauncher had its own problems on my rig. I gues it will be more user friendly to add mods using the steam platform, but as it was told before, this is something that should be implemented in vanilla for all from the beginnig. BIS is presenting ARMA as a simulation, so they should simulate as many aspects of combat as possible and this ALPHA stage is great for such suggestions as this one I guess.

Yeah, Red Orchestra was on my mind when I wrote about this issue. They have done it very well in RO. You can even rest your rifle on doorframe / vertical walls using the other hand as seen on the second picture above.