I think the biggest market will be for people who are looking for a new stove.  I don't see a mass wave of people replacing their old PR's.
I think the chief advantage will be compactness (although the increased durability will be nice).  There are a lot of people who like to take a little mug type pot.  This stove will be really nice for that application.  There are a lot of little solo mug pots that a PR won't fit into but the PR II/MR should fit into quite nicely.  It may well be that its compactness will be its main selling point.
Now, how does the PR II/MR's compactness compare to the competition?  We shall see.  I have a Soto Microregulator, a Snow Peak GS-100, and an Optimus Crux, all of which are in the same general class of stoves.  I'm looking to borrow a Monatauk Gnat.  Compactness may well be what makes or breaks the PR II/MR.   
The PR II/MR is definitely the better of the two stoves from what I've seen so far.
HJ