Thought I'd throw this out there. Currently the Rezound Battery is 50% off at Verizon, it fits in the Thunderbolt with the stock battery cover, not exactly sure about the exact increase in power, but I think it's about 25% more. This may be enough for many to avoid the bulk of the extended battery and maybe just make it through a day, and retain the ability to use the car dock. I'm using it right now, unplugged 3 hours ago and still have 90% left. (Light Use)
I know I saw this info on here somewhere, but just did a quick search, and didn't come up with it.
With this battery, I like my tbolt a little more.