Tough call but in fact I include it on my original list.
But I didn't realize it was a prototype.
If it was intended as a fully-fledged production quality piece and they simply never got around to making any, I'd include it. (Same principle as the Firebird)
If it was only a proof-of-concept and they decided not produce I'd delete it.
The D80-12 has a prototype serial # (LL prefix). My understanding is that it never went into production, but 24 6-string D80s did.