I have had 5 different Grendels. The longer the gas system, the smoother the rifle shoots, and the easier it is to mitigate the already low recoil of the Grendel. Shorter gas systems usually create more recoil, faster operating speeds for the bolt/bolt carrier. I have found that I prefer the rifle length gas systems.
You can change the weight of the buffer regardless of whether you have a rifle, or carbine buffer system. You can also use an adjustable gas system. The smoothest system I have had was a rifle length gas tube, adjustable gas block, with a rifle buffer system that I added one extra heavy weight into. That was one smooth shooting rifle.