I have a pop up 38 and had a Metcalf. Different levels of performance.
I think the Metcalf is the sweet spot of versatilty in MRs line up. Bulky, but works as a daypack. Can do 5 or more days easily. The frame is very capable and you can buyer smaller packs if you want to slim it down.
the pop up is a daypack that can haul on occasion. IMO if you are going to be carrying heavy load often, you should get a full size frame and pack. If, like me, you do a lot of day hunting, you will appreciate the way it handles a days worth of gear while remaining very compact Moving through brush. When I need to haul a heavy load, it works. Not as well as a full size frame, but it works. the pop up would be fine for a light overnight or even two if you packed right, but again, you wont like how it carries as much as a full size pack.