Hi again Bazza,
If you do not plan to go Formula racing, just want an earlier planing light wind board, I don't think you will have any problem with the F-186 from 2002.
Be advised that the F-186 is from the "virtual volume" era, but fortunately, the F-186 has the hghest volume (172 liters) of any of the formula boards from that era.
So, if you can get it at a good price, and you have an 11.0 m2 Retro, you should be all set.
Don't think you will find any larger sails that have more light wind "juice" than the 11.0 m2 Retro.
As far as "hard to control", I think that refers to very high wind conditions in a formula racing scenario.
Very different than what you seem to want.
There may also be some fins larger than 70 cm that might be good for a big guy like you.
GSport (in the Gorge) made some 80 and 85 cm fins (not legal for formula racing) that might help a big guy get going a little sooner.
I had the F-186, and had no trouble sailing it as an early planing board and I only weighed about 165 lbs.
Go for it!