I can understand why the band made the change, Dickenson has a lot more range and the band blew up after Number of the Beast. When Clive Burr left, and they got McBrain (like both drummers, Burr was great, I think he left because of health reasons) the added elements of Dickenson and McBrain opened things up in the music. McBrain plays a lot more busier than Burr had, yet never gets in the way of the songs, and I don’t know if that would had meshed with Di’Anno’s limitations.
I got into the Di’Anno vs Dickenson argument with an all female Maiden tribute band who played a venue every season I did sound at. They go by The Iron Maidens, great tribute band. I held fast with my school of thought lol.