Apple made a big deal about the battery life on the iPad but I find I could easily live with 1/3 to 1/2 the battery life in exchange for weight. I thought about replacing the battery with a smaller one, but it looks like it would not make a whole lot of difference as posted by Kyle Wiens on ifixit.com.
-snip- in case link changes
Here's our summary:
- Aluminum back 138 grams
- Battery 148 grams
- LCD 153 grams
- Glass (and frame) 193 grams
- Speaker: 17 grams
- Main board: 21 grams
- Everything else: 27 grams
