It seems to me that with longer skis comes more area so better float in powder, but this can be achieved with a wider ski. Longer skis will also have a bigger moment of inertia so less easily bounced off line in crud, I suppose. On the other hand bigger moment of inertia means harder to turn in bumps & trees.
I've also been told that longer skis can go faster without chattering. According to my GPS I peaked at 54 mph on my 163 Heads and whilst this is probably puny for the speed freaks out there, I don't want to go any faster, protected only by a helmet and a few layers of nylon.
So, if I am interested in steeps, trees, bumps and only moderate speeds and I have a pair of Icelantic shamans for powder, (161, but an area around the same as a 183 gotama) is there really any advantage to going long?
Concerned skiers want to know.....