My extended battery arrived on Monday. I installed it out of the box on Monday afternoon. It had roughly 78% battery life remaining. I took it down to zero, and charged it up overnight. Driving into work I stopped to get gas. Checked my e-mail, and that was it. It is now at 95%, so I am not seeing any difference in battery use just yet.
I also had a thought on the case. I have a flexible rubber case that I got off of E-bay. It couldn't have cost more than a couple of bucks. Now, this isn't the most elegant solution, but I was thinking I could remove a portion of the back of the rubber case, so that it fits nicely around the phone. I think it will work, but I need an exacto knife of something similar. I also have several screen protectors hanging around. Since they are larger than the new battery covering, I was going to cut one of the protectors so that it will cover the battery cover. That way I will limit the scratches wear/tear on that.
Again...not elegant, but I was going to give it a try. I'll post pics if this comes out ok.