Unsurprisingly, it works as you said it would. Stupid user errors in observation on my part: Soft stops didn't show in MOTU audio level meters until I turned up the trim, and daylight washes out the little indicator dots on the HW mixer screen.
Dynamic allocation does send multiple pipes from one note press to different outputs if the group has more than one.
Pipes moving around don't bother me -- each group of speakers is pretty uniform and coming from the same direction.
That will save me a lot of setting note offsets. Thank you!