[AMA Request] Any engineers that "improperly" use RFC 6598 in their enterprise network

1. What are you using it for?
2. Have you ran into any technical issues while using it?
3. If you had to sell using it to someone else, what were your arguments?
4. Did you tell your SP that you were going to use it? If so, what did they say?
5. Any other comments on it?

EDIT: Disclaimer - This is for educational purposes only.