Thanks Thierry.
Thierry, please don’t take offence that I didn't ask directly: your module is being installed by more and more people since it is a great addition to the instrument and it is possible that others would find this question useful.
' Personally I'd go for version (a). It's cheaper and it remembers the times of electronic pioneering (which is well suited to the theremin).'-Thierry
I like this suggestion :-)