I'm getting 10 plus hours out of a set on the Buzz Pro. I use over 6 mls a day. You might be able to gauge it by that.
I get about 8hrs per charge at about 6mls a day myself. I have 2 sets of batteries also.
I'm doing 1/2 that at most, and I put fresh Trustfires in at 11PM on 7-31-11 and vaping at 5V - and still on the same set with the "Rosco Buzz Pro Edition".