@sns I can answer your questions! The PH9 and 9X are a SUBSTANTIAL improvement over the SWP 9.0 SE. This is the upgrade path I went through. The upgrade from SWP to PH9 was much greater than from going from the 9 to 9X, but the X upgrade is still worth it. I wholeheartedly loved the SWP, but with the PH9 there is just more to everything - musicality, tonal richness, holography, separation, resolution, you name it. I remember opening the box with Vlad Baselkov, owner of Audio Mirror. I installed the stage, and even without tube break in, the improvement of the PH9 was so substantial that it put a smile on both our faces. He immediately bought one for himself the following day.
The ART9 line is also very special. I had the original ART9, and to date it might still be my favorite cartridge despite it being discontinued in favor of the XA and XI. I “upgraded” to other cartridges after breaking the ART9 cantilever. My upgrade path consisted of a Dynavector XV-1s and the TOTL Audio Technica ART1000, and I missed the balance and tonality of the ART9 compared to both of those MSRP $5K cartridges. I sold both of them and am now using an Air Tight PC-1s, which many say is like the ART9 on steroids. I am very happy with it, but it is definitely diminishing returns. In the future I may just find myself going back to the ART9XA or ART9XI.