As a general comment regarding RNP approaches in MEL, I've found over the years that it all goes well, until ATC decide to vector you off, or worse keep you high and then expect you to be back on profile and speed etc.
I even asked the ATCO why clear us for the approach and then vector us off..etc his reply "because that's what we do"
As I said, just a general comment, but it does add complexity to an approach that is further complicated by various operator restrictions and physical limitations.