Thanks for the comments and sorry to take so long responding! 7-week- and 4-year-old kids at home plus full-time school keep me a little busier than usual these days.
I now keep these and most of my other Parvis in baskets or net pots in a mix of limestone gravel, stalite, orchiata bark, and dried sphagnum, with various live mosses (primarily from what I think are genera Polytrichum, Thuidium, and Hypnum) on top or stuffed in side slats. I sometimes vary the proportions depending on species ancestry but I doubt it matters much, and anything from 50-70% total mineral content seems to work okay for the plants and my watering style.
My NH and FD are in the above mix in shallow 10" wire baskets to accommodate their stolons, with both currently showing small new growths. Fumi's Delight grows slowly but is overall truly undemanding; I've left it out in both sub-freezing temps and 95F+ heat in bright sun without apparent stress, ditto for periods when it's been very moist or very dry for long stretches. Most of the year it hangs outside in a shady spot and gets thoroughly watered every 1-3 days, while right now it's wintering in a dark, dry room for lack of a better space.
NYC, if you end up not liking your FD please drop me a line and maybe we can work out a trade, though given how well you grow Armeni White I doubt if cultural problems will be an issue.
Orchid Boy, I've got maybe 12-15 other Parvis, mostly young seedlings for economic reasons. Aside from the malipo x Fanaticum I posted in another thread I have one other first-bloomer I'll try to post soon, and I'll take some leaf shots as well if I have the time. The foliage and habit of these plants certainly make them gorgeous houseplants even when they're not in bloom.