chiming in here: my 733 base unit does seem to eat batteries. Second cook, second set of batteries. When I first got the thing, I pulled it out and played with it, then shut it off with the original batteries in it. Less than two months later, they were dead.
I figured it was just the cheapo batteries they ship with. My replacement batteries made it through a single 9-hour cook - I put the thing away for a week, came back, and the base unit batteries were dead again.
Kind of annoying. The thing works great, otherwise - I don't know how I did without it.