[KWComp]

Couple things you can / should do.

1st - Ditch the HH Pad on the rear. You dont need that agressive of a compound on the rear. You can use whatever brand you want, but just go back to the normal Semi-metallic compound.
2nd - Clean the Rotor with some glass bead blasting. Dont get to carried away, just enough to remove embeded brake pad residue.

 

[KWComp]

I've read when swapping organic to metallic either bead blast or scrub with scotchbrite.

Also, if you wash/wax your bike, clean all that crap off the rotors with rubbing alcohol / brake cleaner.

Finally has anybody considered a rear wheel misalignment? Whether or not that would introduce a squeak by favoring a leading edge?

The Caliper mount hangs on the Axle, if the wheel were crooked it would be crooked with it. :biggrin