Les, this is a great thread, thank you for posting it!
I agree that the Maple neck and the V12 finish versus Mahogany Neck the PS Nitro finish would influence the tone difference, perhaps as much as the SC to DC difference.
I can relate re "there can only be one" - I have the same situation with regards to the SC 594 Prototype. Since it has arrived and I have processed what it is (which took me some time), it is my "one", my Holy Grail. A destination of sorts on the tone journey. It was so disruptive that it caused a bit of a guitar midlife crisis that too my two-year hiatus to fully process and move beyond!
But now I see it clearly - I accept that I will never find another guitar that hits that "classic Singlecut tone" in my head than this one. And I will stop looking, I am okay with that now.
That said, I can still enjoy the different nuances of the 594 lineup and appreciate the differences. My new SC 594 SH, DC 594 HB II and DC 594 Soapbar guitars are all amazing in their own way, keeps it very fun and fresh! Yet still, there can only be one.
I have some thoughts on the Ted McCarty SC 245 PS model and its importance in the lineage to the 594 - I will circle back more on that later...