Sorry for such a late post, especially since I may not have the correct info (as you can see, I rarely post), but this is what I am culling from memory. Also, this reply may not be what I believe, only what I have seen elsewhere.
The supposed advantage of an MC cartridge is less moving mass- not the weight of the cartridge overall, but the weight of the stylus assembly. By moving small coils of wire rather than chunks of magnetic material available at the time, the stylus could more accurately track the high freq grooves (don't confuse this with tracking warped records- only the 'bumps' formed by the cutting head).
Obviously, as in all things 'audiophile', this has been taken to further extremes- if less is better, even less is 'more better'
I believe this is what drives the extremely low output cart- 'mostest less' must be the best!
Personally, I think there is a scientifically valid basis to being able to control less mass more easily, but whether the smaller percentages of overall moving mass coming from the reduction of the few coils is worthwhile could be debatable.
Like you, I have a Benz. My choice was based on which output my pre would accept.