The rotary’s tres kewl (that’s French), but I still like the magnetic slider on the DV-S9. It’s CW, though, but not too objectionable.
Gotta say, the WW on the ’21 looked really nice in the video. Think I have a few 5Ds sitting around doing nothing, may just throw one into a host (or maybe a P90) just to see what it looks like.
(Ah, yes! 5Cs on 20mm, and 5Ds on 16mm.)
Question… is that a potentiometer, with stops on both ends of travel, or a free-spinning encoder? I’m wondering what’d happen after a few years, when the critter starts getting “scratchy”. Oh, and water-resistance.
Yeah, I know, I’m Mr Glass Half-Empty… 
Still, it’s tempting to get one just to play with. 