How to repot Ariocarpus, plus Conophytum ornatum, Copiapoa hypogaea, Thelocactus hexadrophorus, 

could be I'll have to look it up thanks

Maybe a few tiny feeder roots get trimmed but that's it . If you trim roots you have to let the cuts dry in open air for at least a week and I just like to get it all done in one day. Nothing wrong with trimming roots though. I've done it with Ariocarpus retutus once to a sick plant it worked OK.

Good to know. I've found some more info about pruning roots of ariocarpus and cacti in general. It makes sense. In nature, when roots fail to find nutrition, they stop growing. So, the plant grows roots in other directions to find fresh nutrition. All root pruning does is tell the roots "none of y'all are finding nutrition. Grow roots somewhere else." So, I don't think it hurts the plants any as it takes advantage of something the plants will do anyways.