Yes, he was using the NOS 6H23 in both the LS25 MKI and VT100 MKII. Also, He had the LS25 MKII and the VT100 MKIII and liked neither. He claimed that "the magic was missing." He feels strongly that the older versions, with the NOS, were better sounding.
Incidentally, the LS25 MKI with the NOS 6H23 sounds like a different preamp. It became much more powerful, dynamic and robust,with greater slam in the midbass and lower bass. Also, there was greater transparency and richness in the midrange, with a wider and deeper soundstage. In summary, every musical parameter improved, without any downside.