I have no experience on big slalom sails but know very well the maui Sails TR- series and how they behave. Can only say good. Mind their way of expressing power is DIFFERENT from other sails: don't misunderstand lack of lateral pull for lack of power!!! One has to understand that stability in their case is achieved through 1 or 2 more (stiff tube) battens, rather than extra high tension. This is good on the mast (won't break, or at least not as easily as with other sails) AND causes the different behaviour. This should fit your requirements better than most/all other designs.
I have a set of new TR-5's ready fore use now, but didn't put any on the water yet, as is for '09 materials for most people. Anyhow I have rigged them and, from what I see (deeper draft, very smooth even twist, less luff curve), I can expect those to be substantially more powerful than TR-4's and still very soft feeling... we will see.