I have some rock that I got from a local reefer that used the 2-part epoxy to hold some SPS corals down, im sure if the corals were still there it would be fine as they would encrust over that but now I have a rock which has a few blue blobs of silly putty on it and IMO it looks ugly, I use Loctite super glue and it works fine for most things.
http://www.homedepot.ca/product/loct...control/973098