I conditioned the Seidio battery last night thru this afternoon, just as I had done with the HTC battery. When I first installed the Seidio, the phone indicated a 22% charge.
Plugged the phone in for 8 continuous hours, per the instructions on Seidio's packaging (the charging LED turned green after about 2.5 hours). Then turned it off and bumped charged it (it took about another 25 minutes to turn green again once the phone was off). Unplugged and booted the phone, let it run down to 95%, then turned it off and bump charged it again. This time it took about 15 minutes for the LED to go green.
Finally, unplugged the phone and let it run down to zero. I taxed it pretty hard so that it would die before I went to bed. Only took about 4 hours running Pandora with auto-lock off and screen brightness at 25% under 4G. Also streamed a podcast via bluetooth (display off) for about 30 minutes during that span.
Put it on the charger for another 8 hours while I slept. The phone has now been unplugged for 4.75 hours, and shows a charge of 58%. Roughly half of that time was on 4G, with the other half on WiFi. I have had some fairly heavy usage, with about 10 text messages, 30 minutes of web browsing, 30 minutes of Twitter, 30 minutes of Google Listen playback thru external speakers via 3.5mm jack, 30 minutes of Bluetooth audio streaming in my vehicle, and 2 podcast downloads over WiFi that totaled 135MB. All things considered, I think that's pretty respectable battery life.
This is all anecdotal, of course, so the real test will be on Monday and Tuesday when I perform more formal comparisons between the HTC and Seidio batteries. Until then, I don't feel strongly enough either way to express an opinion. Stay tuned.