More battery capacity is always better

What I said above is all subjective, i have not done any measurements!check the thread about battery usage of playing MP3's Vs Ogg and battery life for real numbers.
One of the first things i installed was a visual CPU monitor (called load-applet), and that to me shows how much extra load Javescript heavy sites seem to put on the device (remember that this is *still* not final build software).
My experience with the E90 was that it was the high resolution screen that was one of the *major* contributors to battery drain (couple of times i tried using only the low res (QVGA) external screen and the battery seemed to last longer)

My vote would be for TWIN batteries (i.e 2 small batteries used in sequence).
That way, you could have the best of all worlds;
- lighter (by only having one battery in at a time)
- extreme long life (one battery in use, second in device ready to use, and third on charge)
- device is always on (as you could swap out the exausted battery without powering off the device)