I have a extensive experience of experiencing through demonstration Phonostages, many of which have been compared using a control measure that keeps one system in use.
I am familiar with a Broad Range of Circuits and Topologies that cover both SS and Tube used with a particular system.
Comparing Tube to Tube, SS to SS or Tube to SS, will usually show a difference to the sonic being produced from the used system. It will be conjecture to suggest the same outcome will be repeated on another system.
What I have learned is that Phon's that share similar circuitry and topology, even though not identical, are quite easy to separate into a family sharing similar traits.
Another lesson learned is that even though I am at present a user of Tube Phon's as my preference, I have discovered SS Phon's that I would not hesitate to use for a owned system demonstration, and do believe these models will quite comfortably be considered as keeper devices.
The thing of interest is that Phon's that have been able to make this impression have been with a cost of less than a £1000 and as much as £10000, with a few models that will cost less than 50% of the most expensive.
Phon's that can make a very good impression can be discovered with a very reasonable cost attached to them. The experiences encountered pretty much suggests if a Phon' is discovered that will close the door on all other options, it will be a Phon' with a high retail price approaching the highest, or a model that is bespoke built to meets ones preferences.
If the Phon' in question in this thread is proving to be a match for the qualities being described, it won't be long before the 'cat is really let out of the bag'.