I have my second one coming in and noticed on the website after I placed the order that the latest batch has now switched from 154CM to 420HC.
Probably a smart move from the common uses that have come up from the consumer/user end with fracturing of the tool.
I noticed on a separate thread that there were some changes made on the tool to beef up portions of the tool that would undergo heavier stress to help prevent fracturing. Those issues seems to fixed for the most part.
But still, I'm surprised that not more custom pocket tool makers not use tougher steels for their tools. I've my share of Atwoods chip at the edge, and I would rightly assume this wouldn't have happened if the tool wasn't made of S30V.
Anyways, I'm looking forward to my new Piranha. I was told by PocketToolX that the 420HC was hardened to about 43RC IIRC.