Two other problems I've seen with the 2 part epoxies also.

1. It may mold around the frag fine but you realy need to scrub clear the rock you are attaching it to or the frag and cement will come loose at a later date.

2. it makes my skimmer go nuts when I use it for a day or two - get lots of fine foam.

Didn't realize that about the heat - also trying to mix it with anything but the dryest hands / work surface is an exercise in futility.