Yes. The gunsmith who performed surgery on the AK bolt carrier pictured here had a rifle that he had lightened the carrier and added a buffer. The cycling was so quick the magazine could not keep up, so he had to restrict the amount of gas the piston was fed.
Buffers somewhat protect the gun from wear and tear, and act as a progressive recoil spring. If only a buffer is added, the felt recoil will be different, as will the speed at which the carrier and bolt comes back to battery.
If only the bolt carrier is lightened, it will move quicker fore and aft, and with the original gas system it could move too quickly. The felt recoil will also be different compared to the original. If you combine a buffer and a lightened carrier you should get the best of both worlds. Fine tuning this system will take some time and effort.
As I predicted, the biggest single gain seems to be the gas system. I will try a stock bolt carrier when I get my hands on one.
We tried to time splits when shooting standing at a steel target (1/2 scale IPSC classic) at 70 yards, but the splits were between .7 and .8 seconds with or without the gas restricted. It was a lot easier to get back on target with less gas, as the dot never really left the target. We'll try to shoot a video when we do some more testing to show what it looks like.