I use lots of 3PDT switches in stompboxes, and I find them to be excellent with a very low failure rate. The 3PDT makes a very solid mechanical thunk as it toggles, and some people claim that it is microphonic and causes noise. I have never found the footswitch to be microphonic, but it is a known fact that some high gain effects pedals are! Check out Bill Rupperts’ Effectology tutorial where he is using a Big Muff pedal as a drum (starts around 1:10).
It’s not the switch that’s popping… it’s your high gain pedal.
One alternative to lessen switch noise with microphonic pedals is to use a relay bypass with a soft momentary switch.
Oh, I so want to use the relay bypass you described, but the project is discontinued and the code for the PIC is not available
Now I am considering educating myself to do PIC programming so that I can replicate your project.
The AMZ Relay Bypass uses an AVR microprocessor to control the relay and other functions, but you could use a PIC since that is what others are using for similar projects.
http://www.muzique.com/news/true-bypass-with-relay/
regards, Jack