@txp1 I really like the Gold Lion KT88 in my SLI-80.
Tip: Trust your ears and what you like. A former contact and colleague designed the SLI-100 for Cary. He departed shortly after it was ready to go into production. While the circuit determines the sound with any tube, the KT88s sound very nice in the Cary amps. Sometimes, in some cases, newer is "not always better", fwiw.
This note is coming to you from someone who owns monbock amps that run KT150s or KT120s today. I spent way too much time on my current amps, input tubes, and caps along with different sources trying to get them to provide a sound, tone, texture, and result that sounded closer to my former Cary amps with KT88s, fwiw. While I’ve not heard heard the new SLI-100 in my system and setup, imo, if you love your KT88s now, my bet is the newer unit will sound different, a more modern and more linear sound. KT88s can sound really nice. The old days we use to bring the amps home and try them, not so easy any more with fewer dealers due to manufacturers now offering buy-direct.