"...the FL runs smoother in every way compared to the F6B", that's the line that lost me. I used to have to wear a weightlifting belt on my old sportster not to get the shit shaked out of me and all the way to my 2013 Road Glide that I traded for the F6B and the XL1200 I have now, although they're smoother there is no way it runs smoother than the flat 6. Even my XL to accelerate you crack the throttle, wait for the noise and then it starts to go. When you're on the F6B, you look at a spot, crack the throttle, you're there so quickly you have to slow down not to overrun.