Interested to learn more about experiences using different motors and drill bits. I'm thinking it would be useful to be able to cover a larger area quickly for a very small material removal. For example, after a certain amount of layers, checking the Z plane is flat to a high tolerance. Using different materials and different nozzles could result in small differences that add up over time.
I'm hoping to hop back on the ASMBL train soon, but for now, I've only used square endmills with success. However, Fusion360 offers all sorts of CAM operations, and I don't see why you couldn't also use ball end mills, drills, or larger diameter endmills, provided they fit in the collet and so long as you set up the operations properly. My understanding is that ASMBL is ambivalent to the operation type, so moving beyond sidewall and top surface operations should be possible. You could even do it without ASMBL if you find a Duet-compatible Fusion360 post-processor (Search the Duet3D forum) You might also try asking this in the ASMBL discord thread: https://discord.gg/6XcqsUaq