From what I've read, T foil rudders significantly reduce pitching as well as pitchpoling. It seems the only time they would be a disadvantage is in light air and flat water. How critical is the wing angle? Is there a reliable way to determine the correct angle or is trial and error the best option? I know there are a lot of tech guys here, so it would be great to hear some opinions...

Don't claim to be the expert, most of the T-foil rudders I've read. Angle of attack varies according to wave conditions, speed, and heading. Upwind, foil tuned to lift stern, downwind attempting to hold transom down. Do a search on Paul Bieker for I-14 design thoughts and Formula 60 for the French multihull application.

For what it's worth, my Rave's T-foils on the outer hulls are optimal at 3 deg.

The angle of incidence is critical. A little incidence goes a long way but the best way to find out is by trial and error. You can get an angle meter at Home Depot or "Angle Finder" (same thing) at Ace Hardware for about $20 that is accurate for setup.

I think you will find that a little incidence and the extra foil area makes a big difference in drag in light air but is well worth it once the wind picks up.

We should mention that this same post was made on the Old Forum, and there is some very good technical information posted there by Bill Roberts.

You could also contact John Pearce of Stealth Marine.
He has a production F16 with T foil rudders and I remember seeing a post from him saying they reduced the bow height in the latest model because the T foils prevented the nose from going down off the breese.
He seems pretty convinced they are the way to go.