"I would expect DD backoffs are at least 10x higher and occur much quicker. Most experienced APs don't go near DD games for counting."

Strange juxtaposition of two seemingly antithetical thoughts: "backoffs are 10x higher," BUT ... "APs don't go near DD games for counting." So how does that lead to10x higher backoffs? :-)

Reminds me of a famous Yogiism: "Nobody goes there anymore; it's too crowded." :-)

Don