I think EthanEdwards assessment is pretty spot on. I don't have a L-frame S&W, but have a M27 and 2 K frames. My 27 is more comfortable to shoot with full power loads than the K frames, for sure. But it's a 6" barrel and big and heavy to carry around. The K frames are not very comfortable with full power loads, and I shoot mostly +P 38 spl handloads in them. I've had my M66 since 1974 and it's had the most use. it's still going strong with none of the problems that seem to plague others. Don't know the round count , can't say I've ever keep track of such things.
The L frame seems to be the perfect compromise. I've shot my fathers, now my sons, 686 4" quite a bit and it is more comfortable with full power loads. It carries better than a M27 also.
