I wouldn’t get too het up over mic pre’s to be honest, unless you’re driving them for a particular sound most ‘decent’ pre’s ( and that’s most pre’s theses days) are fine.
The MR/UR pre’s have good history coming from Yamaha. Remember when the O2R came out 20 years ago Roger Nichols did a remix on a steely Dan record he’d done and said the O2R sounded better. hour Glass by James Taylor was recorded using an O2R and that’s one hell of a great sounding record.
MC