I buy Perlite and Peat Moss to my black much also. The all organic
stuff deteriorate so quickly that a level 5 gallon pot will sink 4
inches in a season.
If I had a choice between the two, pick Perlite. The peat will
deteriorate also - the perlite will not.
Jim in So. Calif.

Yes, that's what I assumed. Even the peat moss will eventually
decompose, though the stuff is fibrous enough that some structure may
remain. I just want some mix that will retain permeability for a few
seasons. Certainly true that perlite (or charcoal) should help with
that.