I've had a fair number of high end cartridges from the likes of Lyra and Airtight- usually their top models. The Koetsus- particularly the stone bodies- a Jade and Tiger Eye- really made a qualitative difference in the dimensionality and tone of the bass---something that was unexpected, given the older mythology of the Rosewood that was first brought into the States as a offering a "technicolor" midrange and little else. I think you do benefit from tonearm mass on these cartridges. I'm not daunted by the fact that the company is gone- Expert has a good reputation as does Ana Mighty in France. These cartridges play extremely well on my Airline arm which has considerable horizontal mass. @Lewm- I assume Expert preserved the factory cantilever and only replaced the stylus with appropriate adjustments.