The .30/30 was a great cartridge in 1895!! It will still kill deer. In fact, it will also kill a lot of other critters, some quite large (and tasty, like a moose!!) However, the .30/'06 is an improvement over the .30/30, and is usually chambered in a rifle type which is also an improvement over the rifles usually found chambered for the .30/30.

If you can afford a good .30/'06, why handicap yourself with something less?

You can only shoot as well as you can see thetarget. Most open sights obscure the target, to some degree at least, while a scope does not. I will always opt for a scope sight over irons, if given the opportunity.......