Hello Harrkev,
Is any battery "safe?" <img src="/images/graemlins/smile.gif" alt="" />
Kevin at BatteryStation is testing all of his cells before they ship. He is only shipping cells that test 100% on the ZTS tester. I believe (and know first hand on a limited basis) that the odds for getting good cells from BatteryStation is extremely good.
Keep in mind that there have been problems with all the brands of batteries. They are extremely rare with the premium brands, but they do occur. The ZTS tester came into being because photographers were having problems with their batteries and wanted a way to insure that their equipment would work when they wanted it to.
The ZTS tester is not perfect. As a matter of fact, it seem to lack precision. However, it does a good job of matching cells to keep you out of trouble.
Tom