I do have two of them for my DVX. The contacts don't hold up as well as the Panasonic's. As a result, a stiff breeze or sudden movement will jostle the battery and shut down the camera.
I think the contacts have corroded. I put some velcro strips on them to give them some leverage, so the problem is intermittent now.
...for $40 and have had no problems with it, although I can't say I've torture tested it. It seems to last about as long as the stock battery and fits snugly.