In the end, I just bought a Brother HL-5250DN. Yeah I know, it wasn't in the list, but in the end, the lexmark one (which had postcript+duplex) wasn't available at a nice price, but I thought duplex printing was still a good idea. So I had to decide between a Samsung and a Brother. The Samsung had official Postscript while the Brother supported IPv6.

I ended choosing the Brother one, and it's a good idea. The printer indeed support IPv6, but postscript too. Choosing “Postscript generic driver” in cups works pretty fine.

IPv6 works too, but I faced two (linked) problems:

• mDNS seems to publish the printer through hostname.local/ipv4 and not hostname.local/ipv6
• cups uses only the IP part of the published address, so it uses the IPv4 and not the hostname (which resolves through IPv6 because I've setup mdns6 before mdns4 in /etc/nsswitch.conf)

Another problem in cup is that it doesn't support IPv6-only mDNS. With use-ipv4=no in /etc/avahi/avahi-daemon.conf, no printer can be found. This is #474464, waiting for the maintainer to comment.

At least, it works fine on Linux. Now I'll make some tests on OS X and maybe windows.