We kept these two seedling almost dry during past winter and they developed very good taproot. They growed well during past summer and flowered for the first time in september. They are in 5,5 x 5,5 x 8 cm pots. We use the same treatment as other cactus and they are quite strong plants. As they have a good root they can stay dry for a quite long period (as ariocarpus we think); maybe some tubercles will dry up but after it will produce new ones. During summer we give them water and when the soil is dry we give it onother time. No chemical fertiliser, only natural one.
About shade: they grow greener not in full sun (we use a "shading tissue" on the greenhouse, do not know what is it correct name), but they need light like other "white" astrophytums.

^Thanks heaps for the advice. Much appreciated, great info.

yep, as more propagating gets under way the plant will gradually make the transition to having a permanent place in the hobby. although i think at least in the short-term future it will remain as a choice collectors plant, probably not as common as a domestic ornatum or myriostigma. Unless some commercial nursery in Korea starts mass-producing them by grafting like they do with the albino Gymno mihanovichii's and so the digis start appearing at Bunnings and K-mart.