I'm up to -3 in front with zero toe, and -2.5 in back with .08 degree toe in per side, I mostly drive on track, and highway driving to/from the track, I'm not wearing the inner edges too much and it doesn't give me any trouble on the street.
I think some tracks just give more wear, for example Roebling really beats up the left tires relative to the right if you are fast. Other tracks seem more even, like Sebring and Road Atlanta, and maybe that's because I am slower there
