While these are very stiff picks, they tend to get pretty slippery (at least for me) very fast and wear down quite fast as well. Once they do wear down, they tend to be sharper and less pleasing to use than traditional picks made of more plastic-y materials because there's a little bit of "fraying" to the edges.
When I say they're not as durable as I would like, I weigh that against the benefits of using carbon nylon materials, namely the snappy/stiff feel and the sonic attack of it. They just do not outweigh the drawbacks, in my opinion.
I do like the snappy feel and attack to these picks, and while they may not be as grippy and durable as I'd like, that might be easily chalked up to my hard/aggressive playing style playing mostly 8-string guitars these days.