Why have you limited your choice to those grinders?
As you are making largely espresso-based drinks, the Macap M2M will do what you want it to, is stepped (and easily adjustable), and will save you a couple of hundred bucks. That said, it's not clear what you mean by changing settings 'reliably'....the amount by which you need to adjust the grind is not a constant, so a K3 is also an option I guess. Depends on the reasons for your choice of constraints I guess.
The Varios are the same (but be careful, there are variants within the Vario range).