After reading this thread, I got the 1900 mAh Anker battery. Over a week of use, I 'broke' it in with 5 full charge-full discharge cycles.

the only observation I can make is that with the same phone and same usage patterns, I find that the stock battery lasts about 8% or so longer than the Anker.

I had certainly hoped for more... meh - at least its good for a spare batt.