I run a heavy buffer in 2 of 3 ARs. While you can run the risk of short cycling I have never had to experience it. I've had very few malfunctions of any sort. The buffer does reduce the cycle speed by a little. But hardly noticeable. It also quieted my spring sound and reduced the already minimal recoil.
I would try it and see. If it works and you like it's performance great. If not you learned and won't do it again.
i really like mine!
I have been a silent witness
to all of America's finest hours.
But my finest hour comes
when I am torn into strips and used as bandages
for my wounded comrades on the battlefield,
When I fly at half-mast to honor my soldiers,
Or when I lie in the trembling arms
of a grieving mother
at the graveside of her fallen son.