Little revisit - I went and got a Freeway switch and installed it. Took the opportunity to do a bit of copper shielding while I was in there...
War volume tests this week at band rehearsal, but through headphones I was enjoying all my series options...
IIRC in addition to the standard switching I now have
N+M (series), N+B (parallel), N+B (series), N+M+B (parallel), M+B (series)