As far as I am concerned, I did not know about DS-Lite, so I just read about it (http://www.networkworld.com/community/node/46600
if someone is interested) and it looks like a great system.
As you seem to have some experience with it, do you know systems that implement DS-Lite for the provider-side of the problem?
As for a DS-Lite test, the client-side of DS-Lite would be pretty trivial (a simple IPv4 in IPv6 ensapsulation), wouldn't it?
Or would you like to test the people's ability to set-up a DS-Lite router? I don't think it would be a good test as it would require IPv4 connectivity, and it would be somewhat complex to check that it really makes the difference between packets originating for the same RFC1918 IPv4 address but from different IPv6 addresses.
Anyway, thanks for pointing DS-Lite.