+1 for the anker 2200mah replacement. It's cheaper than the oem battery. It lacks nfc though. And as for the whole "battery memory" thing, don't worry about it. Just pop the new battery in and use it however. I just bought the anker to replace the original battery in my wife's s2, her battery life has doubled.
I just bought the Anker 2200 mAh battery and its great. My phone does last a little longer on standby, but my screen-on time hasn't increased by very much (I typically get about 3-4 hrs screen time).
I'm running CarbonROM + Wildkernel and other various tweaks for battery life. My phone spends most of its time in deep sleep.
When you open your battery stats, what things are taking the most out of your battery? I've found the app Wakelock Detector to help a lot in tracking down battery drains.
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