I think you will get many different answers here, at least till now....
I use a 91,5 cm "short" mast often, with my 1200 Surf wing if a bit lighter wind, other times I use a 100 cm mast, 50/50 I think.
These are the ones I change between whether I want a short one or not.
My 83 cm is too short, I NEVER use it with wave wings, doesnt work at all for me, no maneuverability left (without risking catching an edge of the board) and no fun as you dont "hover" high anymore...
83 cm I only use in 5-7 knots of wind with a bigger marginal wind board, and ONLY if wind is dead onshore, otherwise the normal lengths 90-100.
PF