That Schneider looks amazing Guy and would be the one I'd go for.
Up until your distortion test I'd say totally equal but then seeing how little distortion the SK has totally blew me away, especially on such a wide lens. The specs I've seen on the SK state >0.7% and it show. So it might have slight barrel distortion but its so minute its almost not worth bothering with. The RS is just plain ugly straight out of camera and means another step correcting images.
And I know its doesn't make any difference but the SK will look amazing on your camera!