I have owned the Dynavector 17D3 for some time. It is considered to be very dynamic and fast because of its short diamond cantilever. In my system it was at least 3 levels below the ART9. I mean not even worth comparing.
I have heard the XX2 mk2 multiple times in different systems, it is much better than 17D3. It has a consistently smooth sound picture with a some romanticizing the mids and highs. Macro dynamics are good but below ART9. Microdynamics and transparency is also good but well below the ART9. Resolution is also nice but again not in the same level as ART9. In terms of speed and timing (PRAT) it is similar to ART9 but ART9 is still more agile, more quick with transient response.
I also heard the Dynavector Tai katora Rua, it plays similar to ART9 but ART9 is still more vibrant and energetic in sonic picture. The ART9 just does not allow you to think of an cartridge upgrade because of its amazing all-round performance. It gets out of the picture, plays like top quality studio equipment. Even with the Dynavector TKR I did not hear that level of disappearing act. May be the XV1s does it all and betters the ART9 but I have only heard the XV1s once and that is not a good enough auditioning time to make any judgement between them.