I got a chance to fly the Wind Dancer Sunday with the
stock Speed 400 geared setup, and it's more than adequate... Dr. Drela says that
you can run the SP400 direct, also - the ship is clean enough that it can
make use of the higher speed.
An outrunner or a small, geared brushless would also
work, but you can get this ship flying well for cheap.
Good luck,
Bren
Bren