One of the best antidotes to windsurfing-gear-snobbery is learning to make good with less-fancy-than-your-own equipment while on vacation. I had a wonderful opportunity to do just that recently at my folks' beach house in Edisto Island, South Carolina. The gear that my dad keeps under the porch there consists of a 220 liter Fanatic Viper (85 cm wide beginner board with rubber-coated deck), an ancient 5.7 dacron sail, and a fairly modern 7.8 Aerotech Air-X that I left there a few years ago. I had used the stuff a few times before, but never in more than marginal-planing conditions. Monday, 19 September 2011, had 15 - 20 knots; definitely more than marginal-planing conditions.
Nevertheless, I opted to go for the bigger sail, since it's a better sail all-around, and since I figured the rather-heavy board would benefit from extra horsepower.
I also moved the board's footstraps from their inboard and forward positions to outboard and back positions more suited to well-powered blasting. I didn't move them ALL the way out and back, though, because I didn't think the 44 cm fin on the board would have enough lift to support a fully-outboard stance.
I put the u-joint fairly close to the back of the mast track because the water was rough and I wanted to be sure the nose was riding high enough not to stuff in the waves.
Things felt pretty good on my first run out- plenty of power, but the board was behaving well. A big double concave in the nose smooths out the ride. The footstraps felt like they were out and back enough to get good leverage over the rig and accelerate the board to full speed, but they weren't so far out and back as to cause problems with control in chop or spinning out the fin. The only tuning change I had to make was moving the harness lines back a bit to get the sail fully sheeted. Jibing was awkward compared to the shortboards I'm used to, but the board got around ok once I learned to be a little more patient with it.