I grow all my parvi hybrids in CHC heavily cut with diatomite, spongeroc, and charcoal. A few hybrids and all my species (Fumi's Delight, Fanaticum, micranthum, delenatii) are in bark. I must admit that I like the moisture retention characteristics of the CHC mix a lot better than the bark. However, I'd recomend growing delenatii in bark due to its natural acid substrate.
Edit: I grow everything in bark or CHC, so I guess I shouldn't have replied. Oopsy!