That's what I mean about advantage. None on one code over the other. Marriott divides up the two inventory codes and gives the appropriate number of units to II but once assigned they are identical in terms of staying at MGV. I don't think there are any dedicated one bedroom units. There are 3 bedroom units lock off's, maybe 3 bedroom dedicated units, 2 bedroom dedicated units, 2 bedroom lock off units, and 2 bedrooms that are part of a 3 bedroom lock off, 1 bedrooms that are part of the 2 bedroom lock offs, and studios that could be a part of a 3 bedroom lock off or part of a 2 bedroom lock off. All types of units are assigned to both II codes (MGR and MGV). MGR and MGV units are not assigned in any specific part of the resort and your likelihood of recieveing a newly refurbished unit will not be influence by which code you exchange into.
Once you exchange into one of those 2 codes you will receive a unit type code on the II exchange. That code may indicate which type of unit at the resort you are getting based on the size unit you exchange into. I am not sure if those are in stone and when you call up or arrive you may ask for a different type for example if want a dedicated 2 br vs a lock off one.