Thanks for the thoughtful posts. First of all i'd like to qualify that I sail in the Great Lakes and spend most the summer months on cammed 7.5 or 6.2. and 110 freeride board, or 150 GO. Planing power is a big consideration here, the wind is usually gusty, variable and front based. When your slogging between gusts you have plenty of time to critique your sail's shaping.
Cammed sails are great, and I have one, but I can't help but wonder if everything above the cams is just stalled out and not driving. I just wonder if there's a "softer solution" with fewer mechanical parts and lower rigging tension.
Haven't tried a DS leading edge cammed sail, but forgive me if i'm wrong, most sails like the Pryde RS are high wind blasting sails with low-down shaping, not especially good for improving your planing threshold.
I've been reading about the windward separation bubble/vortex. A big cause of drag i'm assuming. Leeward separation bubbles caused by the mast are worse and can trigger a full on stall.
Really what i'm hoping for in the future is a wing sail with more power for it's size, less mass, adjustable camber, and less torquing effect on the sailor.
I've found some pics of the POWERFOIL which I think was the scottish design from 2001. I'll include them later. Very low aspect with little twist or cord taper towards the top.