I loose speed if I freewheel on descents unless it's steeper than 7-8 %, so I rarely freewheel for more than a few seconds. I guess that brings up the avg. watts (although it is far from registering the watts it should on downhills).
I also still get some slingshots to some extend. I think I missed one at the end while having a good battle with Guy. I was sure he was right behind me, but in a split second he was suddenly 18 seconds in front. Looking at the final sprints in Geoffs video, I'm sure he would have beat me in the sprint anyway

.
The real difference is that I try to set a pace I know I would be able to hold for the entire session, while in the Chain Gang races the pace is dictated by the opponents, and constantly changing.
Interesting to compare stats with Bridgy, who put down 10 watt more but spend 1 more minute. They look very similar, but as far as I can tell, the time difference is due to my higher speed on the downhills, probably because I work on the downhills as well.
Bridgy do you tend to freewheel all the way on downhills?