It's been more than 3 years since I bought Hähnel batteries for my K-3 II cameras.
I haven't kept track of how the performance has been over time but a simple averaging from my last wedding gig summed up to about 800 shots per battery (I used 8 and the 2 last batteries weren't fully used), which is close to what I was getting some years ago, according to
this post.
I recently noticed a change in one or more batteries and need to pay attention to performance. Currently I'm not sure if it's the batteries or the chargers.... or even the cameras.
All in all I must say I've been very happy with the Hähnel batteries.