Ummm, your bayonet would be a bit stubby on a carbine gas system...
Like said above, it less pressure with a longer sight radious thrown in.
Downside is it's a fairly new system that while sort of proven has a bazillion rounds to go to even get close to the time proven carbine gas system in all weather conditions and ammunition.
I have a carbine, mid and intermediate, setup with the right gas port sizes and spring/buffers, I can't tell you one will outlast the other or is any easier to shoot.
That said, given a choice, I'll go midlength when I can but when I grab my Colt light weight, I know it's gonna work.
