At this stage I'm inclined to disagree, Hans...
Note - after closer inspection of the fretboard fotos, I am now certain the triangles are merely stickers covering the original factory dots.
Well, the attraction is - despite it's hideousness - that it is actually a genuine Pilot, albeit of sorts...The present owner was also told by the person he bought it from that it was indeed a prototype, but that would ultimately be quite difficult to prove I think and, I personally don't think it is...
If I am given the opportunity to buy it, I think I would fix this Pilot right up - but the price must be right - it's going to be all about the price...
Some more examples:NEVER knew (or saw previously) that SB-608 necks were born with those triangle inlays...!!!