Terryc: Don't know about the newer stuff, but on my PF5 'tronics the signal first passes through the first stage of the pot, then a resistor, before it splits into a cap bypassing the IC's and another path going through the second stage of the pots.
It's all part of the voodoo of the series electronics!
Germansal, like I mentioned earlier: Even though that guy states that it's only down to changing the pots, he's not telling you the whole truth. There's a nice little bag of resistors and caps that are also part of the equation.
And the switch/pot exchange obviuosly won't make your bass thicker. It would ALREADY need to be thicker to accomodate the taller pots. But since you already have a series instrument that shouldn't be a problem.!