The GEC Prototypes that I can see currently being sold online have the word "Prototype" etched in big letters across the front of the blade. Some knives have "PROTO" etched in a small circular logo in the center of the blade. These are not the knives that have the 'PPP' logo on the back of the blade. These Prototypes generally command a significantly higher price than what the regular production knives retail for. From what I've seen, the GEC Prototypes are usually only made as "1 of 1" or "2 of 2", which makes them more rare than the others.
The GECs that have the 'PPP' on the back of their blades are not Prototypes, they are "Pattern Production Premier" knives. They do not sell for as much as I see the Prototypes sell for, and there are generally more than just a few made. I believe Some of the 'PPP' knives are more rare than others because there were less produced.
I have and would use a pattern production premier knife, but nowadays, the more rare the 'PPP', the less likely I would use or keep it .