DemostiX speaks with great knowledge.
Now something you can do....grab your cordless drill and put in a 1/4 inch bit.
do an official cool looking grad/matrix or go freehand but put a lot of holes in the insert. Since the holes will be trapped between layers they will act as little dead air spaces themselves BUT they will also allow moisture to pass more freely. You'll still get 95% (rough guess depending on the number of holes you drill) of the inserts effectiveness. You don't have to stop at 1/4 inch holes, but I wouldn't go over nickel size ones either.