The substrateless method is just too easy, I wouldn't do it any other way, even with my high dollar clutches...
There's really no need for seal a meal on a substrateless tub set up, the humidity level is easy to reach without it, and with it you have to worry about mold build up.
We switched from vermiculite to perilite mostly because it's cleaner, I like it a lot better than vermiculite.