I have had bad experience with foam. Air circulation in an open space with a goldenrod is better even if it is more of a closet than a safe.
What kind of bad experience have you had?
The reason why I ask is because a friend had two barrels rust overnight while on a trip. When on trips, we always keep our guns in cases and I had a feeling that either some water or sweat dripped on the foam before he put the barrels in the case. The next day, he had rust on two barrels and around the scope mounts. I wonder if perhaps it was moisture from temperature change. When we used the guns, it was probably 95 degrees or more but then we brought the cases back into an air conditioned room and I have wondered if condensation had built up in the cells of the foam and caused the rust.

This is the reason why I oil the snot out of my barrels if I keep them in the foam of my cases. One of my cases has actually built up quite a bit of oil residue in it. Since oils are based from fats, some of these fats degrade to fatty acids over time....and acids are what cause corrosion. So perhaps too much oil isn't a good thing unless a silicone based oil is used.

OK, now I'm babbling on and on.........
Please tell me your bad experience with storing in foam, if you don't mind.