Indeed, if you're single-dosing and brushing the chute (if it exists), then pretty much any grinder that allows chute access for sweeping will work for you. If, as Jim Schulman and Jon (to name a couple of examples) have, single-dosing works for you in terms of consistent result and 'work flow,' then the whole issue of waste becomes moot, and you will want to look for other things. I don't think I'd spring for the Nino if I single-dosed. The doser Robur, IIRC, was better at it. As Michael observed in what does single dosing lose?, the timing function is rendered useless and, in my experience at least, often you have to press the grind button multiple times, even at long time settings (a PITA and potentially bad). The Robur E would have similar, indeed dramatically worse usability problems with single dosing, because it's utterly non-functional (uncontrollable static) without the screen over the chute, and retains probably 5-10 grams in the chute that you can't get with a brush if you do keep the screen on it.

The doser Robur's on-off switch and doser strike me as ideal for single-dosing, if you're OK with doing that. The doser must be swept out at the end of every session, but it acts as an excellent holder for grinds while you sweep the chute and pulse the grinder before finishing off your dosing into the portafilter. It will accumulate a lot more packed coffee cake in the chamber than the Nino, I think, but it's actually easier to take the top carrier out and clean, which is a plus.

If ~$2000 is your grinder price range, I'd go Nino if you want to make drinks with a loaded hopper, Robur if single dosing is your thing. Probably, though, the K10 WBC would serve you just as well (but I've never used it, so I can't say for sure).