The Graupner E-props are the best, (and the most dangerous).
They are sharp, it makes grabing/handling the octocopter dangerous lol.
...get some of these: http://www.envirosafetyproducts.com/stainless-steel-mesh-glove-full-hand.html :tennis:
Yes, mid 80's here. When the same thing happened on my 450 it was low 80's. I don't think it is temp related. They seem to break at the same place leaving about a 1/4 left extending from the hub.