I have owned the VDH MC-One Special which sits below the Frog in the lineup and currently have the Van den Hul Crimson XGW Stradivarius which is above the Frog. I also have the Blue N.S., which I would describe as being a bit more lush than the VDH sound, which tends to be very neutral, at least with the two carts I've owned. The Kiseki had more detail and a little more "magic" than the MC-One, while the Crimson XGW Stradivarius has more detail, great soundstage and imaging, but is still more "flat" (neutral, not flat sounding) than the Kiseki.
If you like that lushness that the Kiseki brings to the table, why not get it retipped vs. buying a new cart, as others have suggested? Sorry I can't speak to the Frog, it may be a different animal than the two VDH carts I have owned.