Boys will be tinkerers. They always have been. The Vintage Forum here is testament to that. I feel an obligation to help my fellow divers understand why their gear works the way it does. I want to share knowledge. What folks do with it is up to them. This nick was a bad one, so the demo was useful for what could be done. There's not enough length left in that piston for another big restoration. If you can't meet specs, then in the dump it goes. Even in the Scubapro technician seminars, the instructors talk about "dressing" a piston. This is merely an extreme example of accepted practice. Now the reader knows how "dressing" should be done properly.
The piston used in the demo was recalled by Scubapro more than 30 years ago. Yet unbelievably, some folks still dive them. See my upcoming thread on how a Mk7 Honker is restored and tuned for more on that.
People make their choices, and take their chances.
The principles used here are what keep my very first regulator still diveable after all this time. I don't take it deep. I don't take it by itself. But as a conversation starter among divers? As a demonstration that tuning and maintenance are 90%, and new technology is 10%? It's perfect!