Just out of curiosity, are you guys rotating front to back or cross rotating? My father had his local honda dealer rotate his tires. They only do a front to rear, and the steering started to pull hard to one side. I did a cross rotation for him and all was well. I usually move the driver's side rear tire to the front, driver's front to the passenger's rear, passenger's rear to passenger's front,passenger's front to the spare, spare to driver's rear. With a 4-tire rotation, I go rear to front, then crossover the fronts to the opposite rear. So far, I've gotten good results on all my cars doing this. This, of course, assumes you're not using those uni-directional performance tires!

BTW, a toyota tech told me that they compensate on the caster (or camber, forgot which one) so the vehicle tracks straight straight when the road has some lateral tilt (for drainage). In other words, the settings for the front tires are offset by a fraction of a degree, meaning tire wear on the driver and passenger side front is uneven.

Anyways, I just mentioned this as a possible remedy you could try yourself for free.