Just my two cents, I've been using a Seidio 1600mAh five days after picking up my phone from a Best Buy preorder. While I do admit there is a noticeable gain in battery life from stock, roughly 1-2 hours, I am considering an extended battery.
As previously mentioned, settings are a huge influence, as well as avoiding thirsty apps, on battery life. I am a moderate user and do all I can to keep this device running for as long as possible. I unplug at 7AM nearly every day, and battery is usually cashed out by 2PM same day on LTE. I keep a charger at my desk, and one in the car, but travel is generally an issue for me, especially with limited places to plug in at a number of airports.
Regardless of specifics, my advice (for what it's worth): if you are light to moderate user, privvy to proper settings, and are looking to drop some cash to gain an extra couple hours without turning your sexy new device into a backpack, go for it. However, if there is even remote concern that it won't be enough to support your needs, you'll likely be disappointed with a 1600mAh.
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