Motor & Bearing or Cartridge upgrade?

The motor and bearing are essential. I am not familiar with your deck in particular, nor the upgrades, but in a general sense there is too much to gain if these upgrades are executed properly. These upgrades are what give your table the ability to hear the cartridge at its best. The Lyra Helikon is no slouch and you will glean much in the way of PRAT from bettering the TT. Any cartridge is ultimately limited by the TT you are mounting it to. Many audiophiles have gone down the path of using a cartridge beyond the ability of their deck, be careful. IMHO build the best table you can before looking for better and better cartridges is the way to go. In my experience with the Linn Sondek Lp12, replacing the bearing was a huge improvement and reduced my surface noise to nearly inaudible levels. The outboard power supply was another huge move in the right direction. My table is not designed for an outboard motor but I have admired the sound from many who have such a feature. I have heard many A/B comparisons with the Linn and its upgrades vs. better cartridges and overall the upgrades to the deck always win out, if that is any help to you. Lets see what people say who have experience with the same TT as you. Happy Listening!