I had the extended battery for about a week before i dedided to send it back. -- To big, different battery cover, (thus hard to switch to the standard unless you plan on carrying the cover too.) cases,(to switch between batteries i'd have to switch cases too.) unless you want a big pda bigger i'd stick with the standard smaller battery. look at the lion battery site for the best deals for extra batteries. I paid $30 for one a couple of weeks ago
http://etxquc.simplyonline.com/default.cfm
To help conserve power I use auto speed and the lowest light setting with the light on. It works fine for me in doors. If you are in the car or outside it can be a little difficult. Games, light, video, and fastest speed take up the most power. task, calendar and reading take up very little.