As an owner of a MMR....and has owned and worked on many WPC machines.
MMR all the way. I would not turn down a MM in great shape but the new electronics you cannot beat. Much more reliable and way easier to repair. No massive solenoid lamp board. Modular ones that can be replaced easier. Much better power supplies, etc. I have had 2 WPC machines with random reboots due to aging caps, etc.
The build quality on the MMR is second to now impossible to tell from the outside its not an original.
I do miss being able to change lamps around (colors, etc). Some 44 sockets on MMR you can do but most are surface mount.
You cannot go wrong with either one BUT if you had to pay 8k for a MM may as well get a MMR. Was cool unboxing a brand new machine like MMR.
Also this is full plywood box, bottom and cabinet. Its not sheet metal back box like some sterns.
My vote is for MMR all the way unless a MM can be had for much cheaper. The fact that the cost of MM's have dropped a lot shows most people would rather buy new MMR then MM. Already 700+ LE's have been shipped and who knows how many on order.