I'm getting great results using 470 ohms on my Ruby 2 into a Klyne SK-2A, going into the MM phono stage of an Audible Illusions M3A. My system is generally very "live" sounding (VTL amp, Wilson speakers), so I prefer the sound of most MC's loaded down. If your system is mellower sounding to begin with, you may prefer the sound with a higher load. I don't think you can reasonably argue that there is only one "correct" loading for a given cartridge. As with everything else in this hobby, it is all system (and sample) dependent.
Enjoy!
Enjoy!