I have been a user and [arguably annoyingly] vocal proponent of IPv6 for over 10 years now. One of the things about this amazing protocol that I've always had a hard time accepting is the lacking support for it more or less across the board. More than that, though, is that it is often forgotten in engineering and architecture projects. The more complicated the feature, the less likely iPv6 support was coded into it and the easier it is to forget.
I've seen many networks that have complex and well engineered QoS schemes, both at the egress points for application shaping and queuing of protocols/applications and across the distributed LAN that only take IPv4 into account. Often the reason for the exclusion was the was a lack of content on IPv6 but sometimes just because it either wasn't supported or it was just forgotten.
Now that the ARIN allocations of IPv4 are nearly depleted and IPv6 allocations are so easy to obtain, not to mention the fact that non-US locations have large v6 deployments and even comcast is doing native IPv6, how are people dealing with IPv6 integration into their networks, specifically related to QoS?
