Yeah, that's why I thought stiffening up the fronts might help - since you're understeering the tires with more grip are the rears - even though it seems kind of backwards for us FWDers.

Regardless, I think the tire pressures might be more helpful. Your best run was with the biggest differential fr/rr. With the rears even lower, you get less understeer, with somewhat predictable traction loss from the rear. I say somewhat because when I first dropped my pressures in the rear, I almost looped it a couple of times because I was used to understeering like crazy and trying to throw the car into turns while trailbraking. The first couple of times with the lower pressures taught me quick I didn't need to do that anymore. Given that changing camber would be a pain in the butt, pressures seem the easiest way to get change.