I have a MR pack fetish of sorts. Among others, I owned a .mil version of the marshal, a Metcalf and now a beartooth.
The Marshall is a huge pack. I think it is more bag than most need for less than 4-5 days. The Metcalf is great. At 70 liters it does fine as a day pack when empty but packs 3-5 days of gear easily and can do more with the right loading. Beartooth is roughly the same size but you give up the snow collar as a loading option.
Unless I was going to make a habit of 5-7+ Day trips, I would think the Marshall is a little too much volume. The difference between 3 days and 5 or more days is mostly food and consumables so I tend to pack those on the meat shelf or strapped to the outside of the pack as needed for longer trips.
So you can do a 9 day hunt with the metcalf as long as you pack it right? I have a while to get it right. This year I am going to be doing 2 5-day scouting trips to the island I am going to be hunting. I will be running the same pack for that so I can get an idea of how I want to pick everything.