I purchased the battery from the OP about three months ago. My phone is rooted with ACS 3.1 I think. Older ROM, works awesome.
Anyways, my battery life is great.
I take my phone off charge at 7:00 A.M.
At 11 P.M. the battery is down to 50-65% depending on how much I used it.
This is the stock Samsung Galaxy S II battery in my Galaxy S I Epic 4G. I purchased my Epic on the day it came out.
I make at least 10 phone calls a day ranging from 2-5 minutes a piece for quick work related duties. I probably send out 15 texts during the day to my wife. Play some Draw Something, browse the web for 30 minutes.
I keep GPS, and bluetooth off all day.
This phone easily can get over 2.5 days of life from me with normal every day use.
I imaging the Razr Maxx would last me a week.
Now please do note that some of you will tear this battery up in a day.
I use my phone less than the average person.
Seeing as I sit in front of a desk eight hours a day I use the web for many things I would normally do on my phone.
I have no widgets on my homescreen. I have no facebook app installed.
I have my SetCPU set to underclock to 800 Mhz and overclock to 1.2 Ghz on demand.
I am very pleased with this battery life.
This battery easily improves the original battery life by 25%.
For about $20, I highly recommend this battery.
P.S. The battery fits perfectly with the stock back cover. It fits very snug. Like perfect. It never even comes close to wanting to bulge off. It looks and feels like the original battery is in my phone. You would never know it unless you read the mah rating.
I hope this helps someone out.