Great info on the cheap batteries I always like an extra in my pocket.
Just so you know it is possible to mod your old 6700 cradle to charge a TP2 Battery. There is a thread on 6700 cradle and I posted pics of my setup. See:
http://forum.ppcgeeks.com/showthread...+cradle&page=3
Just a bit of info on battery charging practices:
NiCad & Nimh - drain completely and recharge completely. They don't like it when they sit around. If you charge a half charged battery all the time you will only get half charge.
Li-ion & Li-Poly - The first 2-5 charges drain completely and recharge. Then it does not matter. I have found that Li-ion like to be totally discharged 1-2 times every few months to keep their capacity like new. These batteries are not supposed to have charge memory like NiCad but they do seem to have some over time.
My two cents...