Theoretically, those caps are subtractive in nature. When the pot is full on, you're technically not hearing the cap at all, minus the value of the potentiometer. It's far more important in amps and pedals, where you have actual signal passing through the caps, and you're using many multiples of them along the signal path. A fistful of ceramics in the signal path would have a cumulative effect on the tone. I hear about guys upgrading the caps in guitars, but you know lots of guitarists leave their tone on 10 all the time anyway. I do use my tone pot, and can't see any reason to upgrade.