One of the things that always strikes me when IPv6 is discussed superficially, is that people seem to assume you will use your ISP provided addressing throughout your internal network. So I'm not sure how that would even work in my case, with two different providers. Everything gets two addresses, one from each? If so then how does a host know which address to use since all its traffic is going to the same router, but may then be forwarded to either of the two Internet routers? I just never got that far when I was configuring and modelling IPv6 for my own interest.