I decided to start this thread as a reference for people having braking issues. I had problems with shudder/chatter on two bikes with a variety of setups. I've finally (i hope) resolved the problem and my brakes work perfectly at all tire pressures.
06 Jake the Snake.
kool stop salmon inserts
*LOTS of toe-in*
the last bit is key. with the stock pads i couldn't run less than 85 psi without chatter. replacing them with the kool stops didn't change much until i toed-in the pads. now braking is smooth, progressive, and powerful. i've got the pad toes almost touching the rims and the heels almost touching the fork.
the best part about this setup is that it's cheap. i almost bought an alpha q fork before i came to my senses and just started adjusting stuff. i think the brakes are under $50 and the fork is the stock kona-branded with an aluminum steerer. nothing on the bike is special or hard to source.