After initial top performance, it now looks not quite as rosy. After just over a year's performance has declined begun. Meanwhile (after one and a half years) holding (both at the same time purchased) batteries only a few minutes. They also have slightly "bloated", so they barely fit into the camera shaft. On request the supplier has merely pointed out that batteries have only 6 months warranty.
The batteries do not last forever is already clear to me, but they wilt after only one and a half years has been weak.