The IPv6 DDoS are rising now, also there is not much protection against it. I dont have a vps or the knowledge about it, but I think that you can affect windows vm's in a vps node with the IPv6 flood attack, so DoS are also possible, I guess.
This looks very interesting from the consumer point of view. Do you think is possible some kind of rating for the providers? I hope you get the resources to finish this project.