I now have both. From the examples I have in my system, the Blue Lace is better - more dynamic, more lifelike. Yes the Coralstone is warmer. I like the Blue Lace better. And in either case the diamond cantilever increases detail and clarity over boron, with no apparent downsides (i.e. it’s NOT more analytical, dry, or bright, which are the negative attributes sometimes associated with increased detail). However, the big problem with the diamond cantilever, even more than its initial cost, is that it more than doubles the rebuild cost. Is it worth it in the long run? I’ll have to answer that question for myself, after I account for how many hours mine lasts before it’s time for a rebuild.
I’ve also acquired the Koetsu SUT (late version), which is currently my favorite SUT for these cartridges (over Sky, Lundahl, EAR, Hashimoto HM-7). I’ve got at least 350 hours on my Blue Lace Diamond now. Many days it’s hard to even enjoy anything else. Though once in a while I really enjoy my Shelter Harmony and/or Accord, and find myself thinking "man, this comes really close". I think the Accord in particular, even more so than its big brother, captures some of the essence and beauty of the Blue Lace in a much less exorbitant package. However, other days the gap seems very large again, with the Blue Lace simply crushing all else.
Big fan of the Blue Lace!