Excellent posts above, most of which I totally agree. To my ear the Rosewood Signature Platinum captures the quintessential Koetsu sound, something that will never disappoint when used in a neutral arm like the Graham. The Onyx sounds to me like Koetsu's tribute to the inevitable, all its considerable glory notwithstanding. Personally, my ear is leaning toward a more agile and neutral cartridge, say the Lyra Helikon, paired with a more romantic arm like the Wheaton Triplanar. But I think the Koetsu/Graham would be an equally appealing antithesis.