I dont like vermiculite for soil. holds too much water. Even at a 50/50 mix with perilite for a hempy it keeps it way too wet.
Perlite for soil? awesome! really can't have too much. Keeps the roots nice and airy. (a little sphagnum moss works nice too, just watch the pH)
Straight perlite? Now you are talking hydro. Totally different ball of wax.