Almost impossible to answer question. Zoom and focus motors use more power than a tape transport. high performance encoders use a lot of power too. What I'm saying is your question is only meaningful under 'all else being equal' conditions but that doesn't happen. Certainly my EX1 can record for around 4 hours of the 60 watt hour battery which is pretty good. The camera does get pretty hot by the end of those 4 hours and does use a fan to stay cool.
Compared to the only other 1/2" tape camera I've used that's about the same however that camera uses 200 WH batteries.

If you want to run a camera all day off one battery the problem is fairly easy to solve regardless of recording to tape or not.

Bob.