Bob,
If I'm not mistaken, the forest/park service wanted these thing affixed to snags because they did not want trees harmed. This put the bags near the ground and out in the open.
I've have never complied with that rule. I have followed the Ursack instructions and tied the bag off ~5' off the ground in a stealth position within bushy trees. I have not had problems in over 10 years.
Most "failures" are user errors both with Ursacks and hard canisters.
