I haven't noticed a volume change at all in any of the three positions, but the tonal difference is highly noticeable, especially between #1 and #2. Less so between #2 and #3. What you say about the 3-way switch makes sense. Why not set it up single coil/parallel/series? Like you, I'm sure I could get the bass controls out of it, but not so sure about getting them back in. I attached a photo of what looks to be a great way of re-installing controls in a hollow body bass or guitar using polypropylene tubing. If I ever have to do it, this looks like a good way.