Carl,

You are focusing on stability only. As I wrote before in this thread, most of the time the T foil provides upwards lift.

When the foil's lift is up, weight must be moved further aft to maintain the same pitch attitude. When lift is upwards the wetted surface is reduced. If this causes a (friction) drag reduction bigger than the foil's drag, their contribution is positive to performance.

Only when the boat pitches down the T foil provides downwards lift. Downward lift increases wetted surface. That adds to the foil drag to slow down the boat. This exchange of speed for stability is usefull when sailing in the limit. The rest of the time moving the weight aft is faster.