Koetsu Blue Lace Onyx vs. Coralstone

It is possible that I have auditioned Koetsu cartridges with not perfect setup ...

Indeed, that is really difficult based on the body which hides the view. You need an alignment System with a dimple that you know when it is done correctly. I have such alignment and even with that one I needed some time ...
Anyway, all I can say, these 2 Koetsus are so different to all other Koetsus I ever listened to that I think, that the Designer made probably some changes and did not communicate that. They are also VERY powerful in their gain, rated with 0.3mV, but I use much lower gain in my preamp than I do usually with carts of such output. Both they have a tremendous punch in the reproduction without any softness.

Thank for your opinion.
I also use Acustical Systems Uni Protractor with USB scope and cart even more dificuld to align than Koetsu.

Diamond cantilever - yes, I think it is most definitely worth it. For those interested in the basis of my opinion, I am using the DC rosewood body with
- trans-fi air bearing tonearm, heroically regulated air supply
- NAS Mentor, machined Al / plywood plinth, new Wave Mechanic and motor
- Sowter transformers with nude Vishay loading resistors
- homebrew cost-no-object electronics
- multiple new generation Quad ESL's with reworked high cost electronics
- 80 KHz ultrasonic record cleaner

I was advised that the DC would harden the sound. I can't comment on a standard KRSP, but the DC makes the music uniquely smooth and elegant. My taste in music is "classical", by which I mean serious music, especially from the Renaissance. Polyphony is especially hard to get right - my system does it, and the DC is an important element thereof. The main difference between my system and live (acoustic) performance is slightly inferior leading and trailing edges - and that is the current research topic (turntable).

DC Fragility? Perhaps, but I have not, as yet, had an issue with that. Just make sure that if you use a coin as a standard weight for your stylus gauge, you use a silver coin, not one of the modern steel ones, as the platinum magnet is unexpectedly strong.

Update

DIY air bearing turntable with 45kg platter makes the Koetsu still better. Clarity without the edge, detail without noise.

Trans-Fi tonearm is weighted with brass weights and deadened with damping material.

And the silver Lundahl transformers don't hurt either.

@terry9 
Very curious about experiences with Koetsu and a silver Lundahl SUT, as I'm eyeing those options right now. Do you have the amorphous core LL1931/1941Ag or a LL1933/1943Ag?

I currently have a Bob's Devices Sky 40 and LL1931 (copper). With my Coralstone I find the amorphous core LL1931 to be much more detailed and transparent, which a much higher level of spatial information (really stunning). However, this comes at the cost of midbass punch, impact, and some of the organic warmth and musical flow the Coralstone is known for. So I was thinking of trying the LL1943Ag, which has a mu-metal core. But maybe the LL1931Ag is so good it addresses the flaws of the copper-wired version?

I find that the LL1931 pairs beautifully with a Shelter Harmony, btw (but the Coralstone is certainly the better cartridge).