I am curious if anyone has had both of these lenses. I have the 19mm elmarit, and it turns out that it will work on full frame nikon if you shave the mirror a little and use a Leitax bayonet. But perhaps this is not really worth it. It seems like the 20mm CV is very nice, but I have not seen too many people using it yet. I think zooms tend to rule in this range (I have a 17-35mm, though I am not that much in love with it optically...it is great in terms of utility though).
Anyway, if anyone has experience with them both, I would be interested in hearing from you.