String spacing is personal preference, no one argued otherwise. Someone said "why not run an actual Music Man thru the Sadowsky preamp?", and the answer is that not everyone cares for actual Music Man. The biggest difference IME does happen to be that spacing is quite narrow on the MM fivers: big difference from 19mm found on Sadowsky and others.
One could make the same argument about Fender: "why not run an actual Fender thru the Sadowsky preamp?" Of course some do exactly this, but most of us here prefer Sadowsky to Fender: we prefer Sadowsky build quality, playability, tone, appearance, customer support, maybe all of the above (plus more). So we buy Sadowsky J over Fender J, and likewise, it makes perfect sense that some will prefer Sadowsky MM to actual MM.