I've been looking for an extended battery for the HTC Droid Eris. I've seen the Seidio 3500 mAh extended battery and the Seidio 1750 mAh extended battery. I don't exactly know the full difference between these two batteries... Can someone please help me understand these two batteries? 3500 mAh: Amazon.com: Seidio Innocell 3500 mAh Extended Life Battery for HTC Droid Eris: Cell Phones & Service 1750 mAh: Amazon.com: Seidio Innocell 1750 mAh Battery for HTC Droid Eris to Seidio Innocell 1750 mAh Battery for HTC Droid Eris/Droid Incredible: Cell Phones & Service My main questions are: 1) How much battery life approx. does each add? 2) Benefits of each battery? 3) Which you suggest?