Add me to the list of refrigerators. However I have found that commercial fondants, or else Michele Foster's recipe, refrigerate better than straight up MMF. I think I've only made two fondant cakes that have not gone in the fridge.
That said, I read a posting here from someone who lived where it is EXTREMELY humid and said that refrigerating was disastrous. I live near the ocean in SoCal so it can get humid, but not really unbearably humid, so I have not experienced that problem. The worst I have ever had was the fondant retained a shine, but I've never lost a decoration nor had it melt into a mess. The advice above about using a cake box is terrific - it is porous so the air can circulate but moisture can escape.
Best way to find out what works in your geographic location is to bake a little test cake and pop it in the fridge...see what happens!