I setup the Rev. C Mini-Me tonight and ran it on 6V in my office. It ran for almost exactly 7 hours until it died.
Starting voltage was 8.6V. Ending voltage was 5.8V. Using a 6V/7AH battery, running the Mini-Me preamp with 48 volt phantom powering MK4V>KC5>CMC6. Most of the time I didn't have a deck connected to the spdif, but that shouldn't matter much, I don't think.
Looks like a 6V/7AH will run for a full show with no problems... festivals the 15hr runtime that Doug experienced with the 12V/7AH would be nice though