As a heavyweight (100 + kg) myself I think that a 9 m2 sail is a goodsend. It is quite a lot more powerful than a 8 m2 for a heavy guy, and it is still decent to handle on teh beach and in transitions.
But in order to use that kind of a sail you need at least 75 cm of width, and with the modern shapes a few more would probably be good.
At least where I sail the wind can be quite variable, on and off, and there can be a longish shlog to the windline. A board that allows me to comfortably pull the big rig is then appreciated, at least 30 liters above weight, preferrably 35.
I find that a two board combo of 140 liters "slalom" + 105 liters FSW pretty much covers all conditions from a very marginal 9 m2 to a well loaded 5.3 (where average weight guys may even sail 4.2).