The MP3DP prints better and faster.
The MPCNC can print larger in the XY and is perfect if you only think you will print once and a while.
I personally treat all my cncs as prototyping machines. They get the job done without a bunch of machines. I just swap the head and go. Yesterday I pulled the laser off and dropped on the 660 and cut out parts for the big machine. then put the extruder on for some test prints. That’s how I use them