I have not had issues but on Gun Broker I have seen descriptions of two S&W revolvers with rust, pitting, or other significant changes to the bluing with the seller describing the changes occurring because the gun had been stored in a gun rug for a prolonged period of time and since then I've been nervous about prolonged storage in a gun rug. I also agree with another post expressing concern about prolonged storage in a foam lined storage case. On the other hand my dad stores his guns "naked" in gun rugs or soft rifle cases and has not had any problems in 50+ years.

The advantage of a gun rug is that if anything upsets the firearms (shelf failure, earthquake, sasquatch) you don't have to worry about your guns scratching each other as they jostle about or fall.

Regarding storage in a high humidity area I like the idea of placing a waxed or lightly oiled gun in a gun sock or wrapping in a clean old discarded cotton clothing item (t-shirt), placing it in a zip-lock bag (get all the air out), and then place it inside a gun rug.