I’m surprised the Shelter 901 Mk III didn’t do what you want. Though I haven’t heard the 901 yet it looks like a Harmony motor in an aluminum body, and that same motor in the Accord (titanium shell) is truly wonderful IMO, and not too far off from Koetsu. You definitely won’t like the Harmony; its dry carbon fiber body leans things out and it’s more about "pursuit of detail".
Benz are a bit warm and full-bodied, but not as much as Koetsu. It’s still a relatively big difference. They also have a lot more treble energy. The Ortofon Cadenza Bronze and (even better) Kontrapunkt "c" are oddballs in their line which sound more Koetsu-like. Nothing else above or below them sounds remotely like Koetsu.
A Koestu with 1254 SUT is just going to be hard to match in the warm / lush department. The treble should not be fatiguing, even in otherwise bright systems. Not sure any other MC can do that. The suggestions for Grado are expected (I still haven’t heard one!). You might also consider the following:
- Find a good re-tipper to keep your Koetsu running long-term. I’m considering contacting Joseph Long / needlestein if Koetsu doesn’t resume production.
- Look at amp & preamp - this can have a HUGE impact on end product sound, and I’ve definitely noticed some carts synergize better with certain amps and/or speakers. When I’ve had brighter speaker & amp combinations, NOTHING other than a Koetsu would sound natural.