Bought a couple on ebay, they work OK. My tech savvy friend tells me if you can find any made in Japan they are probably better.
I think my "spares" are made in China, price was very reasonable, so after a bit of testing, they seem to be acceptable. I did make sure to charge them and use them to test them out right away before I took them on any trips.
They hold a charge well in storage, charge fine in the Leica charger, and give good life in use.
If they had shown any signs of problems, the price is low enough to try some others.
I have had them for more than a year with no complaints.
I also was told by someone working at a major store that the profit on batteries is something like 8X.
I would like to see definitive tests.
Regards, John