[kaerast]

I've run that on all manner of devices and infrastructures and it has never told me I will have any problems on World IPv6 Day. That's not because it is inacurate, it's because the vast majority of setups will continue to work perfectly on June 8th.

[ioshints]

The more out-of-the-box your setup is, the more likely it'll work (modulo a few broken OS/browser combos listed in the ARIN wiki).

You might experience problems in environments where someone has been playing with IPv6 and left it half-broken (or, in my case, tried to be too smart and used DNS server on Cisco router ;)