I just rolled back, and I'm gonna stay on 1.9 for some time.
No matter how many times I succesfully (so the monkey says) apply 2.0 firmware,
the volume and tone differences between strings are still there, on the same models.
It sounds as if they were strings from different guitars. Pity, I'm gonna miss some of the HD models...
I hope the next update works for everyone, not just for some.