Coen Janssen, keyboardist for Epica.
Check this video: https://www.youtube.com/watch?v=0u2eePiXahI
Or see 35:51 onward from this video: https://www.youtube.com/watch?v=SrXRxp-sDVY
Watching those clips, you can see a couple of advantages to that design for a "mobile" keyboard. A keytar design doesn't easily allow for playing with both hands. This does. A flat keyboard mounted the same way could work, but I think for moving around, which is the whole point, it looks like this design provides a better center of gravity.
EDIT: Actually, here is the site for it where they discuss it and have some Epica videos that highlight Coen playing it: https://nu-motion.com/?lang=en
Interesting. In the picture upthread, it looked like the curve was asymmetrical, but it must've just been the angle, and he's a pretty big guy so I guess that's why the keys didn't look full size.
It still seems to me that one of the main selling points is that it isn't laid out like a keytar. For people instantly turned off by the keytar design, I suppose that's a plus. The ability to use both hands is definitely a plus. The only thing, therefore, distinguishing the Revo-1 from any other controller that you could mount and wear around is the curved shape, because it would otherwise look like someone just mounted a controller on a harness so they could walk around with it (which is basically what it is). So the curve distracts from that. A guy walking around with a keyboard attached to his waist would look kinda stupid, but if it's a
curved keyboard, then that's obviously much cooler (sarcasm, but of indeterminate degree).
So for keyboardists, the choices would seem to be the keytar design ("you're trying to look like a guitarist!"), this (which kinda screams "gimmick" but at least isn't a keytar) or fixing a regular keyboard with a strap and wearing it in front of you (which I've seen but can't find a picture for). Or just standing behind your keys.