[davidmanze]

Who was talking about taking 4 out being the end of the world?  It is nicer when 1 battery lasts the day, and I think it is a bother when you want to charge more than 1 battery and have to do that in-camera. That were my contemplations about the implementation.

Of course it would be nicer, lot's of things would be nicer, however I always pack a spare battery when out for the day, either with K3 or the Nikon. I never contemplate charging. 

I'd probably pack two spares for a mirror-less, it's just the way it is, the nature of the beast!