OK I finally got around to listening to my old (boron cantilever) Coralstone back to back against the new (diamond cantilever) Coralstone.
Before listening I measured the output of both with a test record and the new cartridge is 5.5 dB higher than the old one. I am not sure if this is because Koetsu has increased the output or because my used cartridge has fallen in output over the years. (It is 4.5 years old and had about 2500 Hrs on it.)
Also, I have only managed to put 4.8 Hrs on the new cartridge so it is nowhere near to being broken in and I haven't done the critical VTA adjustment. Nonetheless I had to do the back to back listening test. I played that same 2nd side of the Speaker's Corner reissue of the Firebird and matched levels with a dB meter so that the peak was 99 dBC on both.
What stood out was that individual notes seem much more "distinct" with the new cartridge. The "blattiness" of the horns was more pronounced. The sense of the recording space and the low level echoes from various instruments were more apparent. Overall the recording sounded more natural and much closer to the experience of hearing a live symphony in the concert hall. Now to break it in and do the fine adjustments to get even more out of it!
Here is a link to a google drive folder with samples from both cartridges in it. I normalized the recording from the boron cantilever cartridge so you don't have to adjust volume to match levels. I am interested in any comments from people who listen to these files.
https://drive.google.com/folderview?id=0B2ceYgRGBXdbTVBoeWViYnpLSGc&usp=sharing