I went from a 78mm Rossi B2 to 84 Fischer Motive. The B2s are definitely better in the bumps, but that has more to do with having softer tails than the Motives. The Motives are still pretty decent in all bumps except for hard pack bumps where the stiffer tails can get hung up a little bit on the back side of the bump.
That said, for overall performance, the Motives blow away the B2s. Quicker edge to edge, better hold, better in crud......too narrow for powder deeper than six inches though.
I have not skied the S80s, but wouldn't think you'd notice much of a difference. The difference in length will probably take more of you getting used to than the width.