Just a couple of small things:
This is sort of a follow-on to your more complete implementation of the inches/mm preference setting (and thanks again for that!). The units in the comments section of the g-code output are always in mm, regardless of choice of G20/G21. Whether or not the units in the comments change along with G20/G21, there should be a header comment to say what the units are.
I’ve tried enabling “Token spacer” for my machine, but the setting of the checkbox doesn’t stick, and has no effect.