Because I already own the NA28 since a month I noticed that the text changed in 1Pe 1,23, 2,25 and 5,2 (first αλλα) from αλλα to αλλ. You can watch that phenomenon even in 1Corinthians(!) in Chapter 7,4 (both αλλα modified to αλλ!), Vers 7 and 10, all changed from αλλα to αλλ! I have to add that I only read two chapters (1Pe 1 and 1Co 7, rest of 1Pe I searched out of curiosity) in context since I have the NA28 so it doesnīt look like these are rare.
I donīt know if you also notice orthographical text changes. I think itīs pretty interesting.