I use undestr and nodecay. I have reports from players that certain things that spawn in the zone, IE* Boats, Air Balloon, Minicopters do not take damage, or decay.

Now, I have been able to test "Minicopter" damage in the zone, and found that it couldn't be damaged. I took it outside the zone and it would become damagable. Not sure about the boat or air balloon, haven't been able to test those yet. 
Reason why i even tested the minicopter is because using TruePVE I had to reconfig to allow damage and found that it didnt allow in the zone.