I have young big cories and pygmy cories on mine, but I will say that it feels extremely soft on my fingers. It's the softest thing possible I imagine besides a bare bottom. I love it because they can sift in it and the sand/water stays very clean.
The other good thing about it is that the "medium" size is small enough to be easily sifted by the fish but heavy enough to not end up in the water column. Which is good if you care about the longevity of your filtration, etc.
The myth of sharp substrates being bad for Corydoras is just that - a myth. It stems from about 16-17 years ago when Cories hit a popularity peak.
Reality? Pretty much every issue involving barbel damage involved poor tank husbandry and questionable water parameters. Basically unclean, less than ideal living conditions. And sometimes some uncycled tanks. There were even some wild claims about Turface being problematic (it wasn't) back then. There have been a couple issues here and there that could potentially be related to sharp substrates. But I can't remember more than a couple out of a hundred or so others here on the forum.
All it took was a couple random "expert" websites (that no longer exist) to publish a couple poorly researched stories and, bam, the myth took off.