I would hope that PlusNet has valid, well-thought-out reasons for deploying CGN instead of IPv6. Not knowing those, I can only jugde their position on its face: foolish and short-sighted.
Move along, nothing to see here. Barring a few fanatics, everyone here has known for several years now that CGN would be required for continuing IPv4 support regardless of the progress of IPv6.
If you spin it right, it's a "Free network-based firewall to be installed next month. Opt out here if you don't want it." And the fewer than 1 in 10 folks who opt out really aren't a problem.
Even tough you have very good arguments, my suggestion would be to have a class A network (I got that right, right?) for all the users and only having 6rd as service on that network. -- //fredan http://tlmc.fredan.se