Can't speak to the 4" or LA specifically but I have the 3" and love it. Very quiet, smooth road mannerisms very capable on the trails (only limitations have been many other lacking mods
). Ride on road is better than OEM imo. Two close friends have RE 3.5 SF and say the FT rides smoother on road. All the parts seem very HD and quality, no sag at all, settled at the 3" as advertised. But I'm not going to sit here and compare it to RE or RK on the trail.