The genuine Newnigma2-Image for dm600/dm500+ was indeed released for a short time, but then was withdrawn, short after the release! The reason were some major failures in this image. So it could possibly be that the announced image is the real deal, but i would not install it because of the explained reasons.
"Remember, if it's psychobilly, it's gotta have some rockabilly in it somwhere. It ain't just punk with a double bass." (P.Paul Fenech)