I had a chance to try the Angenieux in the M1 and the Bell & Howell versions as well as the Zeika Nominar (all 25/0.95 and c-mount). I'm not too much into pixel peeping, so I really only looked from a user perspective with no ambitions for professional work or large prints. I did not see a difference between the two Angenieux lenses in IQ, but I felt that the B&H handled a bit nicer for my taste - it's a touch heavier and feels more 'substantial. But that is really marginal. The Zeika is a bit softer wide open but handles nicely because the focus ring is a bit farther away from the adapter. However, that lens is missing the front ring that has the filter thread, and I don't know if/how that affects the picture quality.
For myself, I decided to keep the Angenieux B&H; still have the Zeika and an extra B&H but they will go up for sale if I ever find the time.... I like the pictures from the B&H, and especially in the 1:1 format I can easily live with the minimal vignetting. For me, that limits the excitement about the new CV lens, I can live with the small inconveniences and enjoy using the smaller and lighter legacy lens. After all, it is really more a specialty lens that is great to have but the situations when you use it's full potential are rare in my experience.
Stefan