Found this may be useful or not.
http://getipv6.info/index.php/Customer_problems_that_could_occur
:thumb:
I've just come across this site (http://test-ipv6.com/faq.html). Lots of helpful information as well as a speed test.
There's also a link to a useful network & IPv6 tester (http://netalyzr.icsi.berkeley.edu/m=testv6)