I have a 7290 with the extended battery. i have had it for about a week now.
With the regular battery:
After 12 hours, I would have 50%-55% of battery life.
With the extended battery:
After 60 hours (and no charging), I still have 30% battery life.
This is with normal use and auto off for 5 hours per night.
I am glad that I have it. I don't think that you'll be disappointed.