hey guys,
I'll try to give you a pic of my newly setup with this stuff. It really is very nice. It holds rocks very well, but it is hard to get it to stay very well on vertical surfaces. So whatever you are doing you will have to lay it flat so that you can get it horizontal.
I would definitely use some small pieces of rock and also some very coarse... like caribsea seafloor mix on it. You could probably add the caribsea seafloor mix a minute after you've sprayed it and wait about 5 minutes before you drop the larger pieces of rock in it or they will just sink into the foam... although it creates these cool little pockets in the foam.
I didn't use seafloor and just used large pieces of rock, but I'm going to be working hard on growing stuff on the wall and also hope that coralline takes a liking to the stuff.
Peace,
John H.