My first couple of stays at M were on a comp. After I played I went to the host office (right off the casino floor near the hotel elevators/Baby Cakes) and asked the host on duty to review my play. I told the host we wanted to have dinner at the steak house, Terzetto, and asked how much I had available to use. I was given a figure and told to charge it to my room and it would be taken care of, but you do have to go back to the host office upon check out to make sure -- it doesn't seem to be automatic. I did this on both of those first stays. The second time I went over the "figure" they gave me and they took care of that, too.
They do remove $100 per night from your available comps for a regular room there, so play needs to be somewhat substantial to get comps over and above. If I remember right, they comp 30% of your theoretical loss. Just for something to compare to, here is my play for those two trips:
1-30-----$18,278 coin in (even)
1-31-----$20,418 coin in (won $3091)
This trip they comped off a $150 dinner.
2-27-----$21,159 coin in (won $3000)
This trip they told me I had $100 available, but ended up comping off $120.
All of my play was on video poker.
