bdp24, I really don't know what you are trying to say. Using a mono cartridge that was built from a stereo cartridge by internally bridging the two channels is precisely the same thing electrically as using the mono switch on a preamplifier. Bridging, either inside the cartridge body or at the mono switch, has the effect of cancelling the surface noise from a mono LP, just as you say, by cancelling the signal derived from vertical movement of the stylus tip. One could argue that deriving the mono signal at the linestage level is possibly less effective than doing it inside the cartridge, because the stereo signal has to pass through RIAA correction and amplification before the noise can be cancelled. Maybe, just maybe, doing it at the cartridge body is audibly more effective. Which is one reason (besides the fact that in one of my two systems I have not even a mono switch) that I too am curious to acquire a mono cartridge.
I would wager that 90% or more of "mono" cartridges in the current marketplace are derived by internal bridging. Have fun trying to figure out which cartridges (other than Miyajima, EMT, and perhaps one of the Ortofons) are "true" mono cartridges, if you want to find out whether that is a better way to go; most manufacturers use a lot of double-talk in describing their mono cartridges such that it is usually impossible to be sure. I know this because I spent a great deal of time at their various websites researching mono cartridges and came away disappointed by the total lack of clarity, again with the exception of Miyajima.
I would wager that 90% or more of "mono" cartridges in the current marketplace are derived by internal bridging. Have fun trying to figure out which cartridges (other than Miyajima, EMT, and perhaps one of the Ortofons) are "true" mono cartridges, if you want to find out whether that is a better way to go; most manufacturers use a lot of double-talk in describing their mono cartridges such that it is usually impossible to be sure. I know this because I spent a great deal of time at their various websites researching mono cartridges and came away disappointed by the total lack of clarity, again with the exception of Miyajima.