I own a Koetsu Urushi and like it very much, but I always ranked it slightly below my favorite LOMC, which has lately been the ZYX Universe (the original version). Recently, I mounted the Urushi in an 18g Ortofon LH9000 headshell and connected that to my Kenwood L07D tonearm, after the Urushi sat aside in its box for about 5-6 years. For some reason, this raises the level of performance of my particular sample by quite a bit. I am now enjoying it like it was a brand new toy, even though I've owned it for about 10 years. This piques my curiosity regarding Platinum and stone-bodied Koetsus in general, but not enough to induce me to shell out the $$$ required to own one of those models.
By the way, with any reasonable phono stage generating enough gain for an MM cartridge, a SUT with 1:10 step-up ratio should be more than sufficient for all but Platinum version Koetsus. I was surprised to read that so many are using 1:20. I am using no SUT, of course.