My apologies - I did not spot that you'd changed the encoder command options. I was about to suggest that a warning isn't necessary, provided the --help output details the change, and then I discovered it does! Maybe a warning would help after all :-)

Anyway, with the VOLU command it controls the volume very nicely. A small/slow click can be made to trigger a +1 or -1, but most twists of the encoder trigger a larger increment. It seems to be counting properly to me.