Well I just tried 6s2p A123 - 20.2V on the batteries and it armed fine.
This was on a brand new MM - I ran it in the basement for a few mins and seemed fine.
Don't think I'd trust it but wanted to see if it would arm. It did!
That's impressive. I wouldn't mind running an MM on 5s A123 in a savage until the MMM came out. Was that a fully charged A123 pack. I'm confused with A123 voltages.