I've been trying to program a third party footcontroller to reliably turn stomps on and off for ages now. The fundamental problem is that there is no way for the controller to know the current state (on or off) of any given stomp before it sends its first message. So we get into these scenarios where we have to load a rig, then stomp on all the pedals a couple of times to get the KPA and the controller sync'd up. And if you're trying to translate messages from a device that will only send PC's, (i.e. the same value on every press) then you're completely out of luck.
I think this would be immensely valuable to anyone using generic third-party controllers:
In addition to the on (1) and off (0) CC messages associated with each stomp (ABCD), the KPA should also respond to some other arbitrary value (maybe 127, maybe anything other than 0 or 1) by toggling that stomp slot. That is, turn it off if it is on, turn it on if it is off. This would apply to CC's 17, 18, 19, 20, 22, 24, 26, and 28.
PLEASE PLEASE PLEASE PLEASE. I thought I could get by just jumping between rigs to turn effects on and off, but even with otherwise identical rigs, I hear a "pop" that isn't acceptable for the purpose.