I had an interesting one tonight. Guy caught me up and drafted me for a bit, then procceded to undertake me on my left, boot it through the traffic at close quarters and hammer down a shared path. I choose to take a nicer approach and move with the traffic and then filter off onto the path when there was room before cycling at a sensible speed on the path. Just thought he was a tosser.
Personally I don't draft, I hang back and take it easy for a bit or power by and keep the speed up.