~10+ years ago I was eligible for the MMP & MMF rates. One of my relatives worked at a Residence Inn. Discounts were very deep during that time period. Initially rooms at $25-50/night when normal rates were typically $150+/night; however, the nights were ineligible for stay credit and elite benefits. Over time the discount levels declined but were still quite good. Marriott also reclassified the rates to be eligible for stay credit and elite benefits.

Fast forward to today, I wish I was still eligible for those rates. It may be time to make a new friend who is a Marriott employee. Anyway for those who are eligible for these rates, they are great with no downside that I am aware of. Enjoy....

--Jon

P.S. As others have already noted in the thread, the properties will know who gave you the form. Any bad behavior by the guest, criticism of the property, etc. can potentially blowback on the employee who sponsored you for the rate. When I used the rate, I'd be a perfect model guest. Even if there were valid issues where constructive criticism could be given, I would refrain. I didn't want to cause any issues for the relative who was a Marriott employee who sponsored me.