Black sable tube how good?

I’ve seen these tubes costing double of what some favorable Tubes are costing.
I was looking at the 6922 type.
I thought they made a big difference in my Pro-ject Tube Box phono preamp.  Definitely worth the money, IMO.  I think they used 12Ax7s or 12AT7s.   No experience with the 6922s.  My CD player uses them and I replaced the stock tubes with some vintage Amperex from Vintage Tube Services.  I think I paid about 180 for the pair, but well worth it. 
What makes them different ? Are they just cherry picked , matched triodes with top specs? Are they cryo?  I think I would just trust a guy like Jim McShane or Brent Jesse if i'm going to spend 100 bucks on a 12ax7 or 6922 .....   
Just buy 60s amperex 7308 white label or 60s siemens gray shield from a reputable dealer. If you really want to try new production tube, try genalex gold lion. 
I use a Gold Lion 6922 in my c-j Classic 2SE.... only tube to last long other than Volkshod 6n23eb  in my experience in that pre...   sounds great,  long life.