It works for me........I could care less about the lock, but I am a huge fan of the K and L frame RB grip frame. The 4" HB RB Model 10 is one of my favorite guns of all time. It just works for me with standard RB Magnas, it may not be everyone's favorite but it's mine.
The round butt worked on the K-frame since 1899, and S&W just went back to the original grip. I think it's pretty neat, after 102 years of the M&P-Model 10, the RB has been in constant production.