I have the Shuguang Treasure 6SN7s on my Don Sachs preamp. Don says in his website that these simply walk away from the holy grail NOS tubes. That's quite a statement.
Obviously this is not the case with all NOS tubes...as a lot of the culture that made these tubes is gone forever.
All of our customers that have installed some of these boutique tubes say the same thing- that the Psvane, TJMusic and so on have all the best qualities of the best NOS tubes without the weaknesses.
I can confirm that the Shugang plant that made the garden variety of 6SN7 burned down about 2 1/2 years ago. Also, FWIW every example we've seen of the Sophia 6SN7 has been weak. We've only seen them installed in customer equipment, and so far when asked no-one has said they were in the equipment for more than 6 months. So we think this tube has a defect causing a short lifespan; NOS tubes will last for years in our stuff.
So far the Linlai tube seems to be a better part. I'm hoping it has a good lifespan as I mentioned earlier; if this is the case the tube is a steal at its price.