The big question for me is whether the minority of available mono cartridges that are built for mono from the ground up (which means they have little or no vertical compliance and no capacity to respond in stereo to the groove modulations) are intrinsically superior in reproduction to the rest.My cartridge is vertically compliant but does not transmit any signal in the vertical plane. When the needle drops to the record surface, it makes no sound, whereas my AT150Sa makes a very loud THUMP!
When I play a munged up mono record with any stereo cartridge, the surface noise is unbearable. When I play the same record with the AT-MONO3/LP, all I hear is the music.
As I said before, I got my AT-MONO3/LP cart for a paltry $112. and change. KABUSA's mono switch is $229. My tonearm uses interchangeable headshells, so switching to the mono cart takes very little time including balancing and resetting the VTF.
If, however, I had a tonearm with integrated headshell and had to swap carts on one of those every time I had a hankering for mono, you can bet I'd buy the KABUSA mono switch instead.
I still stand by that modern mono carts with vertical compliance are a good thing as long as the cart doesn't transmit signal in the vertical plane.