I only use Duracell ULTRA's in mine and easily make it through a standard 3 hour, 2 set show. I had a bad run using regular Duracell and Energizer regular batteries, so I would suggest staying away from those. I also bought a pair of Powerex rechargables and had hoped those would get me through a regular show, but they are only reliable for about 1 hour.
As for gain I run at about 11:00, Lo gain with Schoeps cmc64's.
hope that helps.
Brian