Very expensive, true for the alleged 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 4-fold 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.

Personally I think I prefer a replacement stock and renew if necessary ...

Conclusion:

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