Charles, I think we are all a little loose with our language. Add to that the trite nature of electronic mediums, and we inherit the whirlwind so to speak.
Your elaboration of purity and thereness is good. A vivid palpability or "presence" minus mechanical artifacts is a solid foundation. For me, that magical presence also involves ambient energy. A lot of systems I have heard, whether SET, OTL, push pull tube, or SS, fail in that area. You have the soundstage clearly delineated with good depth, clear, 3D images, and yet the whole thing is limpid and static. Pretty sounding hifi.
I believe ambient energy is linked to dynamics. If a system is not capable of lifelike dynamics, the absence of any mechanical edge is irrelevant. As Maril555 pointed out in a Coincident Frankenstein amp thread, SPLs in a concert hall are on average 85 dB with peaks at 100 dB. If an amp/speaker inteface cannot pull that off, its a mismatch. This is purely a matter of physics and not personal taste.
Another ripple to add to the equation is power. Clean power and SOTA power conditioning adds all the things we have been talking about here regardless of amplification type. I was involved in an after hours demo of Miguel Alvarez's Tripoint Orion in a SS system at the recent Axpona. It utterly transformed the sound, and provided the most palpable images I heard there. So, the thing that is most often forgotten is somehow the most important. I have had similar experiences with Dale Pitcher's new Theorem conditioner. Without it, the system sounds broken regardless of what's upstream (I am not a dealer for either company).
As for the TRL Dude/Samson cocktail, it does not sound SET-like in the traditional sense. Due to the Samson's transparency, the speaker and source are uber important. Paul and Brian are big on master tape, and I understand why.
In terms of pure logic, Tellefsen needs to demo other speakers. I know that is painful, but if you like what the Viva does, it makes sense.
