Yes I would become an mp6. I think of an mp6 more as someone who has specific goals that they would like to accomplish and the mp6 uses their mp6 powers to further those goals. For my character the main goal is to sail West from Golemus, but that goal has many sub goals as well. Gather a crew, fix the Lighhouse, get a boat, gather supplies. Only after doing all those things (and a few ones we don't know to do yet) will Rophs be able to finally sail to the Westlands. The power and inherent leadership given by the sixth mindpower would help my character immensely in doing all of these seemingly impossible things.
edit: I've never been mp6 because I've never tried to become one. The main reason for that is I've never been a capped mp5.
edit:fixed a typo