I actually started bowhunting and went to rifles. One rule of thumb a frend and very good shot told me was spend as much on your glass as your rifle. I con't say I always have, but I don't scrimp either, and it's paid off with both rifle scopes and binoculars.@Desert Dog your first point is something I hadn't thought of, and while binoculars would help determining if there was anything behind the target they may not help identifying obstructions in the bullets path.
And yes I have heard that optics have advanced considerably and while possibly not at resistant to bumps as irons they are by now quite dependable. But the cost! I'm not sure I could justify almost doubling the cost of my rifle to add a quality scope and rings.
So, take that as a plus or a minus. If you stick with iron sights and plan on putting together one good long range rifle remember that rule it will pay off.