So, nothing yet from JC but I bought the Kleos anyway.
OMG! This is apparently the cartridge the Sig 9/Scoutmaster needed in my system. Has stronger upper highs than my Shelter 501 II, speed/slam, really nice bottom end, full (not overdone) mids, AND plenty of detail without being harsh. I heard reverb on Paul McCartney's voice in places I had not heard before. Guitars are wonderful and the way this cart reproduces piano is probably illegal.
About the speed, as many of you have probably experienced, often you get speed in the form of the leading edge of the note but not the fullness or the decay. The Kleos gets it all. More of the "In the room" bit than I am used to hearing form this system.
I am hearing some sibilance that probably should not be there so I may need to go to 1.8g as I am a bit below that. Also at 100ohms and it probably needs more. Left the VTA where the Shelter was so there is probably some work to be done there. Overall it is a shade raw sounding but I suspect that is a breakin and setup issue. It is not what I would call harsh.
Y'all be cool,
Robert