Jezza some of the no cam freeride sails are suprisingly competent.
They make for easy rigging and are usually easier to control, albeit less stability and top end. They'd probably have more power down low so you could get on the plane faster. That said I can keep within 5kn of some guys with full race gear across the wind on my wavesail/freestyle board combo. Most of the diff is how you sail no really what you sail.
I sailed a KA Koyote for about half an hour before I realised it had no cams! It was still very fast and easier to gybe. My mate sailed the Turbo in the 2011 LOC and did quite well in the ocean race he said it was a nice forgivable sail, you should also check out Severne Convert. Both KA and Severne freeride sails are made with full x-ply so should take a bit of a flogging. Severne Turbo and Convert are new for 2011. The equivalents were the Focus and Element for 2010.
I weight ~85kg I'd probably go a 7-7.5m for 16-25kn but your board is a monster @ 131 so it might get a bit crazy at higher wind strengths with a 7.5 you could afford to go smaller if you plan on keeping that board. Beauty of newer sails is you can pull them down and depower them heaps. More windrange.
I wouldn't bother to size a sail for less than ~16kn its too light and is just frustrating sailing, pick a sail to suit your usual wind strength.
Hunt through seabreeze buy and sell for some cheap gear.
http://www.severnesails.com/2010/index.html <--- To check out 2010 stuff
www.kasail.com/windsurfing/www.seabreeze.com.au/classifieds/default.aspxOh and if your still unsure ask around to demo stuff before you spend yer hard earned cabbage.