I'll still take a 30% stretch dynamic rope over a 5% stretch static rope fall any day. My math might be wrong, but 30% is 6X more shock absorbing than 5%, even if the amount of rope is 1 foot. The last time I fell it was about 3 feet (when the strap on my stick slipped out), add in the amount of rope around the tree, and the amount of rope is now more like 6 feet. I don't even want to think about the forces my back would have felt if I had been using static rope.
I have a couple of questions....
What's the drawbacks of using a dynamic rope?
If it adds in a factor of safety, even if a small amount, why not use it?