[DrBob]

The VS800 is designed to be very quick, with light weight and gearing to maximize low-end acceleration. But there is a trade off for all that bottom-end grunt: the 800 tops out at about 108 MPH. And you are in top gear fairly soon, which is why everyone keeps saying they would like a sixth gear to bring the revs down at highway speed.
The 1400 is heavier and more stable on the highway, and is more comfortable at 80 MPH that the 800 is, with a less busy motor. The 800 pulls like the dickens up to about 75, then starts to run out of steam, where the 1400 pulls strong up to about 100, and tops out at something like 125 or more (I have never actually found the top end on a 1400 before).
For years the 800 was actually faster than the 1400, but the newer 800s are not as fast as the older ones. The difference, I believe, comes from the different ignition curve in the post-1998 control box, which will not work with the older bikes and vice-versa. The single-carb version of the 800 motor in the Volusia is a LOT slower than the dual-carb VS version, and the version in the 800 Marauder was somewhere in between the two. The version put in the VX800 sport bike was identical to the VS motor, but with a vacuum fuel pump instead of an electric one. But because of the highway gearing on the shaft drive, the VX was actually slower than the cruiser version stoplight to stoplight.