Thanks! Hadn’t seen that approach before. So there are three things happening there:
1. Phase switch - hot becomes ground, and ground becomes hot.
2. Slight level reduction with the series resistor.
3. Bass cut with the series capacitor.
Having just been playing with the bass cut capacitor on my 4620, I know how that can really open up the mids, since it removes the lower-frequency cancellation interaction between the two pickups. If you then put the higher frequencies out of phase, that should make the upper frequencies thinner. Is that essentially correct (even though it’s an over-simplification)?