Anyone ever have, use or hear this tube?

Absolutely!

The G73R were manufactured for medical and military applications that required zero level of noise.  The glass was specially developed to ensure RFI & EFI shielding.  The tube is superior to the ECC802S - but as always, your mileage may vary.  Also, the tube is extremely long lived, with may claiming a 40,000 hour tube!

I became aware of the Apos Ray tubes recently.

Would definitely give them a shot.

Please keep us in the loop on these.

they also mis-identify OLD stock tubes, making basic mistakes like asserting that philips-labelled EI yugoslavia tubes, of which they sent me several pics clearly showing EI yugo codes,  are really philips. https://www.tubedepot.com/products/7dj8-pcc88

Just FYI, cey,  Phillips was a Dutch conglomerate that owned many brands of tubes and would often put one factory's label on another factory's tube.  They would also brand tubes from factories they owned as Phillips.  EI was owned by Phillips.  Here is a link to the codes for all the various brands and factories Phillips owned:

Phillips Manufacturing Codes - Google Search