Almost all of my cakes are doctored box mixes and i've never had a problem with any of them.

I decorate for fun. I have always had a freezer and have tried almost everything but cake batter. That is definitely on my to-do list . I have frozen portions of finished cakes - fondant covered and bc covered - with great results. Just let them come to room temp slowly and don't touch until "dry". I did not freeze any gumpaste decorations, though, so I don't know about that. I did leave a well-wrapped fondant-covered cake in the freezer for over three months. It was brightly colored (red, white, and blue) and there was no running or smearing of colors, and the cake was pretty much like fresh.