I think the misconception that windsurfers don`t adjust their sails while sailing is similar to observing a weekend Hobie 16 /Dart 18 sailor who is not racing, and claim the same thing. He will set downhaul etc on the beach and just go sailing, if conditions change, he`ll come into the beach, add downhaul and go out again.
When racing windsurfers such as the Formula class or Longboard class, which are both raced windward/leeward courses, the sailors adjust outhaul while sailing, and in the Mistral class (the previous Olympic board) the sailors had 36:1 downhaul adjustable from the boom. Most modern windsurf rigs don`t require adjustable downhauls as the manufacturers have optimised the twist in the sail set at the optimal downhaul setting, which is printed on the sail. By dropping the outhaul at the weather mark, the sailor gets more power low down where it`s needed, and increases the twist in the leech, also good for downwind speed.
Anyone who does not acknowledge that windsurfer sails are far more aerodynamically superior to cat sails has clearly not seen the sails developed for racing, with wide luff sleeves and camber inducers. But that`s not saying these types of sails would work on a catamaran - they probably wouldn`t you would need to build a lot less twist into the sail for starters. Check out the attached pic if you disagree..