I went for the mono II as AT say it has a richer sound and my favourite stereo cartridge is the SPU Royal N. Most of my mono discs are classical.
Playing it through the 1:26 SUT I bought for another SPU (the Century), which loads it at around 76Ω, somewhat below the 100Ω+ AT recommend. Doesn’t seem to bloat the bass the way too low a resistance would with the superline but with only 5 hours on it so far that might change.
This microgroove of Beecham conducting some Berlioz is filling the space between the speakers in a most stereo like manner after a my preliminary VTA adjustment.