We are in the same boat too.
We use most all the Atlassian tools internally and try our best to make consistent L&F on our in house web services as well.
I was just taking the weekend to update an internal web site that used AUI5 and I wanted to spruce it up. I started working with 7 when I came across this. Now that I can’t use it, I will probably move to 6 or replace the AUI completely… Much more work that I wanted to do.