Finally gave this a try as a shortcut to Plat. Did a one hour interview meeting on May 8th and the nights/points posted today. Probably won't do this again since I'm a long way from points for Lifetime anything, but at least I'll be Plat next year (as soon as my Sat night stays posts)
It was actually pretty painless. The only thing I noticed is that the form I sent in didn't have a space for my Marriott number so I wrote it in next to my signature before scanning/sending the form back.