Whilst I don't know much about the chemical aspects of Perlite & Vermiculite
(other than they are supposedly chemically inert), I do know that here in the
UK they are widely used in CP composts. I have not used Vermiculite, but I
have used Perlite successfully for several years in conjunction with peat and
sharp sand for Sarracenia composts, and in conjunction with Sphagnum for
Nepenthes and Darlingtonia.
The only downside I have found is that Perlite doesn't look too pretty on the
surface of the pots - cover it up with something else!
Bruce Doswell
bwgd@eworld.com