That's the way Total Contact was. $300 for 1.5ml seems excessive, until you realize it is enough to do everything in the whole system and then coat the bus bars, breaker connections, and neutral and ground wire connections in the panel. So basically the whole system and panel. Which takes hours to do, but when done the improvement is what you said, amazing darkness between notes, incredible depth, detail and definition, yet this all comes with no edge or glare, in fact the sound becomes much more smooth and natural.
The acid test to see if it really is a good copy of TC, does it work when applied on the outside of wires, caps, drivers, etc? Because TC, and all the related stuff, is much more than contact enhancement.