The load numbers look wrong, mine start at 3ohms and go up to 40ohms.
I think a 100ohm load would have little gain.
I'm of the 'I don't care' school and use the setting that sounds best.
VAS MC One Transformer
I bought this years ago, and I think a MkII has come out since. Since I'm currently using two MC cartridges, and there's a bit of hum using the Quad 24p phono stage in MC mode, I found it and slipped it in and switched the Quad to MM. Certainly cures the hum!
A question re loading. As I understand it the 47kΩ of the MM input of the phono stage is now irrelevant, only the low (47Ω) or high (100Ω) inputs of the transformer matter?