[dsl]

Yeah, everyone treats non-routable space as a security control. So expect to only see DMZs and edges of networks in the routable IPv6 space.

[ghshephard]

Non Routability has a really bad reputation, but enterprise/corporate IT people are fond of it.

The nice meet-in-the-middle approach is to use a RFC 4193 space + NAT-PT. Gives you close to best of both worlds - you get end-end connectivity, but full address portability with little effort when you change ISPs.