It is possible that Scandium is less durable than carbon steel or stainless steel, but the real question is ....... Does it matter?

A large percentage of steel firearms, especially S&Ws last two or three lifetimes. So if a scandium or titanium firearm only lasts one or two lifetimes, is that really an issue to be worried about?

As with any new material or construction technique, things may turn up. S&W will fix them

When stainless revovlers were introduced in the 1960s it was quickly learned that the sear engagement would get ruined after several thousand rounds went through the firearm. So S&W stopped using stainless steel to manufacture triggers and hammers. Problem solved.

Scandium has been around long enough that the little things have already been worked out. How long scandium revolvers will last probably won't be known in our lifetime.

BTW, I have about a dozen scandium revolvers myself. Amazing that an 5" N-frame can weigh in a few ounces lighter than a model 19.