Quite expensive, true for the power increase?

Duracell is synonymous with long-life batteries and also ensure a good reason.
Nevertheless, there are now considerably cheaper manufacturers who in Performance / longevity definitely not have to hide.
Here come to mind primarily the batteries from LIDL that, my personal favorites are the basis of my experiences.

So why the 3.5 times pay more?

Everyone needs to decide for itself, I personally see no reason.
Because in my experience, keep expensive brand batteries, if at all, only slightly longer.

And as long as you do not buy entirely unknown batteries you have to not really worry about the safety outlet.
Here I have also not made any worse experience than with the expensive brand batteries with the discounters.

The integrated tester is a nice gimmick but honestly; Who is this, except at the first touch of the batteries use?
Who builds from batteries and checks to see how much capacity is still available?

Personally I think I prefer a replacement stock and renew if necessary, because the batteries are empty it shows without tester ...

Conclusion:

Definitely good batteries but quite expensive.
Whether a good feeling and the eventual durability are the value must each decide for themselves ...