[aiharkness]

I think you are doing ok with the 9900 if you can make it through the day without having to charge or swap out the battery while using the device the way you need. Charging every night when you sleep would be better, anyway, regardless how long the battery would go otherwise. If you change your habits and need more and can't charge during the day, a spare battery is the way to go.

And I agree you wont find an OS that significantly increases battery life.