Prince 2 is just a methodology - common sense with new names! It should take about 4 days to qualify. I have seen some real thickys with that qualification, I know - I is one! Comparing it with an MBA is like comparing oranges and carrots.
As for opening doors, it all depends what you want to do. Having been in business for 19 years since leaving, I think that the MBA has passed its sell by date.
Stik