Having done both (Open sighted Double, Open sighted Bolt Action and Scoped Rifle), it is definately easier with a scoped rifle, no too ways about it.

Except when you are in the middle of a herd of cows and calves
and I will agree with the above comment that they can be really dangerous, if not more so than other buff. But as he also says, Big, trophy buffalo have an attitude all to themselves sometimes.

Getting up close to Aust Bulls can be a problem on flood plains.

Anyway, each to their own.