@chakster - your recommendations are interesting. I have decided to stick with my Linn K9 cartridge/ Linn Ittok LVll moving magnet combo for right now. You see, yesterday I finally made an executive decision about how to move forward with my upgrades.
I needed to decide about the Linn Karousel bearing promotion that was ending on 6/30. In order to get the Karousel bearing for "free" I had to commit to purchase (order placed) $4,000 USD in Linn products. I elected to put all of the $$ into the power supply and I ordered the "Akurate" level of "Radikal" DC motor and power supply. These Linn naming conventions are bizarre but Oh well....
But I have been listening to the K9 cartridge through my Bryston MM phono stage and it sounds really good. No reason to mess with success right now. I will have to fully audition the difference that the Karousel bearing and the Radikal power supply make on the sound quality of the LP12 Sondek.
By the way, I decided also to purchase the Greenstreet Audio aluminum subchassis (Keel copy) in order to hopefully get the most out of the Karousel bearing upgrade without having to pay the exorbitant cost of the Keel subchassis.
So changing cartridges does not appear to be necessary at this point. I will re-visit that option after all these exciting changes are implemented.