I'm curious too, but I do know that Marriott is dialed in with how easy it is to attain Plat here in various ways.
I have Gold w/ MR. Earned the hard way.
PC gave me a status match to PC Plat.
Just for the heck of it, I hit up MR with my PC Plat status to see if they'd upgrade me (cheesy, I know....). MR told me that they upgrade PC members based SOLELY on nights count, irrelevant of PC status.