If it's true that the internal SUTs on the Shindo phono sections are not as good as easily available outboard SUTs, then why spend money on the Shindo phono stages that have MC inputs, since in all cases the added gain is achieved via built-in SUTs. If Shindo make an MM only phono stage, that would be the one to buy, just from a cost-effective point of view.
The market agrees with you. The updated Monbrison only has MM input because most buyers prefer to bring their own SUT. Also appealing is the new version's use of output transformers, intended to lower the preamp's output impedance from 5000 to 600 ohms.