Here is the Mule fully assembled. You can see the cable stops so he can go multi speed should he so desire.
The ENO hub, disc brake, curvy seat stays, and bridge. It all works.
Honestly, it has to be seen in person. It is really a striking bicycle.
OK, now down to the future fun. ButterCupII with a further shortened head tube to fit Devos more svelte frame. And how about reducing the wheel gap to 22mm, ala Jimbos ride. Lighter weight, stiffer(probably not noticable), and quicker handling. I would also remove the Pacenti chainstay brace.