This is a very interesting light. I would like to see it with infinitely adjustable brightness option, however. And I think in many situations, the dual button interface might be better than a ring. While fun, a control ring isn't really secure because once turned on, you then have to be careful how you handle the light otherwise you risk moving the ring. I don't like that "fragility" aspect. I think flashlight UI's are still very simplistic and need much more work and thought. The common pressing, holding, double clicking, soft pressing, etc.--it all works, but it's all cumbersome and there have to be better ways.
I like this Klarus (and Fenix too) 2-button idea, but 3 buttons might be the sweet spot. Buttons plus a control ring might be a solution too--you can choose to require a button press to "unlock" the soft (i.e. continuously rotating) ring. Anyway there are lots of possibilities but the rear clicky or tight/loose head that you see on every light, is actually pretty bad except maybe for some tactical applications--but 95% of buyers/readers here don't belong to that group, except in their minds.