If that is the case where you sail, I would vote for Formula, even after I criticized it. I won't comment on your goals (I think nobody could), there are still many ifs and potential problems as PG says.
"up to 20 knots formula with ONLY ONE sail ONE board is enough. I have been sailing in FE the other day with Overdrive 11.0 in 28 knots with my 70 kilos...still possible."
This is the kind of comment that can create a lot of misunderstanding and confusion among less informed sailors (to put it very mildly).
After all the good discussion on these forums related to strong wind board choice (iS, Kombats, etc), I think most people can judge credibility of such claims.