Brake pad formulation is a VERY complex task. The engineers have to balance cold, hot, wet, dry, high speed, low speed, rotor wear, heat transfer to calipers....etc All I am saying in the end brake pads are a compomise. If you change pads to fix one compaint you might create another.

 

I have a similar problem with my brakes, only it occurs all the time, not just when they are wet. I read that some people replace their back pads. I'm thinking about replacing my front pads, and possibly the rotors. Think that will help?