Matt--
I kind of like your idea because it raises a lot of good questions. Keeping in mind that I am NOT a sailor, here's my question:

The purpose of the outriggers on a tri are to provide bouyency/lift to counteract the tendency of a narrow hull to heel excessivly in the wind. If the outrigger is a foil it will, as you point out, provide more lift at higher boat speeds (a good thing). But it will provide zero lift at no boat speed. I guess this is an example of dynamic stability/static instability. To me it appears that some outrigger volume (bouyency) will be required to get going, but once underway the foil outrigger would seem to have at least some potential.

Mike