Well after 100 plus hours on the New CV181-z. I think they went to soft for me. They sound a little dark to my ears compared NOS Mullards ECC32 The new CV181-Z are good but to me not as good as the NOS Mullards but this is just in my system.
My experience too ... yes they are good tubes, I'd put them sonically on par with a Sylvania GTB, which, at their retail or discounted eBay price, stretches the value equation. I really was hoping for a modern 6SN7 compatible tube that could give me what I hear from a late-fourties early-fifties era Ken-Rad, Sylvania, RCA, or Raytheon VT-231 or GT. Those have magic, the Shuguang CV181-Z not so much. Still I'm glad to see a tube manufacturer pay attention to sonics and I hope Shuguang or New Sensor or someone else redoubles effort for the 6SN7 grail.