I guess what I meant is that I think it's a necessary component of gruyere - but it's a very small component. But that also probably comes with my messing around with Beaufort (really, Abondance) makes - Beaufort is quite low in propionic, compared to Gruyere (and higher in salt level, so, doubly acting against any kind of pronounced propionic character). And I was once piqued by Francois's comment on the natural propionic in alpine forage. Alp mentions L'Etivaz, a small area of strict traditionalists I hold a ton of respect for (man - I love their cheese); want to visit and see firsthand what they do. I'd also love to see a chemical breakdown of their cheeses and forage - to see what they start with in terms of alpine grasses, herbs, flowers.
Anyway, just my thoughts, sounds cool what you're doing.