Ok.. got my battery last night! First off, the place that shipped it got it here on Monday when Amazon estimated Wednesday at first, then moved it to Friday. So I'm already impressed with the third party provider.
Photos are attached.
First is the G2x with regular battery (and no TPU case that I normally keep it in)
Second is the 2800 mAh battery sticking in it for reference
Third is with the 2800 mAh case on.
I charged to 100 yesterday, and it's been running for the last 23 ½ hours, and it's at 40% currently. I've been using the hell out of it too just trying to kill it: Draw Something, Defender, texts, google chats, email, WiFi on all the time (but again, JD is running).
It's obviously bottom-heavy now with this beast in it, so that's taking some getting used to. I actually like it when the phone is being held vertically, but it kind of drives me crazy when I'm holding it horizontally. I'm sure I'll get used to it.
One thing that screws with all my plans - LG released 2.3.4 update yesterday too before I knew this battery was here, so I unrooted, flashed the updated and re-rooted. I'm now running 2.3.4 stock/root rather than my EB AOSP ISC ROM I was running before. I thought I'd have 3-4 days before the battery was here.
Anyway, more updates as I manage to kill this thing and see how it goes.
EDIT - going to bed. 29 and a half hours into first charge, at 30% currently. Will update tomorrow after work, once I 0 it out and recharge.
EDIT - 44 hours on first charge, almost exactly. Monday night at 7:47 to Wednesday afternoon at 3:51. Starting charge up now.
EDIT 3 - Uploading some usage photos. I think I'm an idiot when it comes to Battery Monitor Widget. Frankly most of this just doesn't mean anything to me, and the place I think I should see mAh estimate shows nothing. Anyway, this is normal daily usage - mostly some chatting, email, WiFi (because work appears to be build in some kind cellular Faraday Cage), lots of Draw Something, Temple Run and Defender 2. For some reason Defender doesn't show up.
Edit 4 - These screens were taken at 6%, and it easily could have lasted more time. I just wanted to charge it up and be done for the night.
Anyway, after a week or so of using this, I think it's a solid battery, but one that I'll probably pack away as a spare for weekend trips when I don't have access to a charger. I have dedicated chargers at home and work, so battery life isn't much of a concern.
For $12 I got this battery, a free USB "universal" card reader, and very fast shipping. Totally worth it.