I have found myself using a hybrid approach this past 2 years with UR. I buy 2 flights, points 2-4 flights (depending on who of my 6 family members is traveling), and then use points for hotel. It is a bit of a logistics dance but my fault for having a family of 6!

My fear of having a hybrid MR/UR point system is it'll make that dance more complicated (maybe). Then again, maybe it'll open up options with more partners on the MR cards!