If my experience is any guide, you'll find the Raceboard sail super grunty, with a lot of low-end power, but lacking in top end speed. That's fine in light winds, of course - however with my old-style slalom boards I struggled to get upwind with the Raceboard sails because their extra power comes with extra sideforce, so the fin is very heavily loaded. IF you're just reaching around they can be lots of fun because you can get up and hooting when most people with similar-size sails are slogging.

I'm not sure a modern slalom board would suit the Raceboard sail better than the old boards despite the extra width of the new board, because the mast-forward position of the old gear should suit Raceboard sails better.

Thanks for the input Gents. I suppose with the larger slalom boards, most have deep tuttle boxes so not a big expense to put a bigger fin in, which will again reduce the top end, but it is all about planing and not slogging. Interesting combo a 9.5 raceboard sail on JP SLW that would probably get on the plane just as quick as a formula board!