Dickinson is more about the energy and the connection with his audience than being technically perfect. Does he strain to hit some of the notes in these older tracks? Of course he does. He originally sang these tunes back in the early 80's, so it should come as no surprise to anyone that he struggles with some of the higher notes.
One thing Bruce is really good at though; he does a very fine job of finding a way to sing the songs and not leave any big smelly clams in his wake.
As for his "front man" skills...he's one of the best. Definitely in my top 5, maybe even my top 3.