I was surprised to see how small the stock battery was on this thing.
I think my imagio had a slightly larger capacity.
I had upgraded my imagio to the 3200 mAh with the larger cover which I didn't mind because it made it easier to hold onto. (I dropped that phone all the dang time before that).
With that extended batter my imagio would almost last all day with heavy internet use vs barely making it to lunch time.
With my TB I can't even make it to lunch time if I use it heavy.
Of course the screen is larger, the processor is twice as fast and with 4G I'm using more data.
Anyway. I'd LOVE a 3200 mAh for this TB but I have that nice three piece protective cover from Best Buy that I love. I'd have to literally dremel a square hole out of the back of it if I wanted to use that huge battery. :-(
I'm surprised you are seeing much of a difference with that slightly better than stock capacity battery.