I bought the Seidio 1750 about a week ago. I figured that, all things being equal and the price difference for the extended over the stock being somewhat nominal, that I would rather have the higher capacity battery (without having to change out the back of the phone).
I followed the recommended battery conditioning steps (5-6 full charge/discharge cycles) and so far am rather discouraged by it's performance.
I used to have a Hero, so I use that as basically a 'charging station' for whatever battery is not in the phone.
Whereas a fully charged HTC stock battery coming out of charging on the Hero and inserted into the Evo would retain the full charge for many days and still only drop from 100% to 98% upon start-up of the phone. The Seidio will drop from 100% to 93% just from powering up the phone.
It (1750) does seem to drain quickly at first, then levels off in the high 80's and drains slower the rest of the day.
I DO seem to get more juice out of it than the stock, maybe about 1.5 - 2 hours more, which is good. But basically it just feels like another stock battery and not necessarily a replacement of the stock as my "primary" battery. I don't want to swap batteries everyday, so I would rather have one that I use most of the time and have a back up for when I travel or are going to be out for a long time.
Also, equally discouraging, is it feels flimsy. When I got it, the tape that surrounds the cell / battery felt loose and you can physically bend the battery a little (the edges that case the cells). The stock feels more solid and the material doesn't "bunch" up when you insert it like with the 1750.
Anyway, it's an extra battery that works. However I am wary of using the Seidio as my back-up only battery, since it does not seem to retain it's charge very well (when not in the phone and just sitting in my laptop bag / pocket).
Lately too, I seem to be getting a lot better performance and time out of the stock. Not sure what it is, I think it has to do with up-time, but it seems to be getting better with time, lasting longer. Maybe the same will be said about the Seidio when I have had it longer.
Anyone else have it (1750) and getting great performance from it? I am a pretty heavy user, WiFi on most of the day, always checking my phone, playing a game, internet, WordFeud, FB etc.
I'll unplug at 7am, usually charge it back up on the drive to work so that I am at 100 when I get to the office (9 am) and am usually at between 40%-60% at the end of work (6pm) and then charge up again on the drive home.