Here's my assessment. Preface, every Mon-Fri I use the phone almost exactly the same - 7am unplug the phone and use it till 14% battery left or I go to bed (which ever comes first). I make several calls during the day, use WiFi where all day, GPS stays on, Bluetooth stays off (exceptions noted below). I gave each battery a full 5 days of use, and averaged them out over the 5 days. I also noted the maximum % of battery life was left for extreme circumstances consideration. Seidio 1750 would range anywhere from 40% by bedtime (11pm ish) to needing a charge by bedtime. HTC 1500 would range from 40% to 20% by bedtime (11pm ish). That is correct, I have not needed to charge my 1500 on my weekdays. Here's the kicker. With the Seidio, I had only 3 radios running all day, and never used Bluetooth. With the HTC, I had 3 radios running all day and turned on Bluetooth for my drive home (used speakerphone instead when I had the Seidio in there.) We all know Bluetooth is a battery hog, and the 1500 has lasted me longer life than the Seidio has. THIS IS BY NO MEANS A SCIENTIFIC TEST. My point is that the Seidio cost me $50 shipped. The HTC cost me $15 shipped. Even if my extra performance from the HTC were a fluke, to have equal (or near equal) performance from a battery that costs less than 1/3 of the Seidio makes it the winner. In my situation, the HTC 1500 mAH is leaps and bounds better than the Seidio. What also finalizes my opinion on the HTC > Seidio is the fact that I emailed and PM'd Seidio directly asking about batteryboss's claims, as well as what I've observed. I've never received any reply in response either way (be it email or PM on this site.) I'm not saying Seidio is a junk company, because they've outlasted all other batteries I've had for my BlackBerry smart phones. In fact, I've sworn by Seidio, but ever since an OEM battery has been available to me for CHEAP I've put Seidio as a second choice in extended batteries. I hope this clarifies a lot of debate. Don't flame, take what I've gotten as anecdotal. What you have with your Seidio may be different than mine. But, my issues with the battery have gone by the wayside with the HTC 1500 (though I still feel HTC should have equipped the phone with this instead of the 1300, but that's another story). I LOVE THIS PHONE! UPDATE: Gave the 1500mAH to my girlfriend, and she also can go a full day without needing a charge. Again, for $15 you can't go wrong.