Audio Note members re going from M3 Line to M6 phono

I am considering selling my AN UK M3 Line and purchasing the AN M6 phono. Because I use a Denon DL103 MC I will also have to get an SUT. There is about a $4000 cdn difference in the value of my M3 and the M6.

Or should I just spend the money on a Audio Note Phono stage for the M3

What about the SUT? Or forget the SUT  and just spend the money an a good MM cartridge instead.

My TT is an LP12 with the Rb300 Audio Note arm.

Thanks in advance for your suggestions.