Congrats on the K10!

If it were me I'd put steel burrs in the Vario and sell the Rocky. With the steel burrs, the Vario is one of the best grinders for drip coffee on the market. I've never owned a Rocky, but from what I've heard, it is a dependable workhorse but not really capable of excellence in any area. And although some people have problems with slightly wandering grind settings on the Vario, that won't really be a problem for making drip coffee, given that small variations in grind size won't be as detectable there.

K10 for espresso and a steel-burr Vario for drip would be a pretty awesome grinder collection, IMO.