OH MY GAWD. Arturia DRUMBRUTE came listening to MIDI channel 10 for note messages.
I read in one part of the documentation that it only listens to start/stop messages, but in other parts it says it sends note MIDI info if you set it up in the (Windows and Mac only) MIDI control center software. That implies it listens to note messages. More burrowing in sparse documentation on MIDI suggested that's true. Playing a pattern that sweeps all the notes in Renoise while changing the channel found joy on the tenth try. Your mileage may vary.
This message posted for posterity.
I'd still like to hear comments about the original question, even though no way am I getting rid of this DRUMBRUTE now that it's exactly what I want. :)