The one blip in SAF's career was the early part at Man U. Which of course is somewhat analogous to where Ange is right now. I would stress tho that SAF arrived at Man U having pulled off an almost incredible managerial feat over a few years at Aberdeen. Ange has a decent CV, but nowhere close to SAF on arrival in Div 1.
How many times have Australians have managed in Europe's top leagues?
About as many times as Aberdeen have won the UEFA Cup.
Ange doesn't have a decent CV, he has a CV that has never been done before, that's better than decent.
Not saying he's going to be SAF but as you say the early struggles were worth sticking it out for UTD and they are for us with Ange.