I'm late getting to the thread, but my thoughts on iron sights.. I like them, don't get me wrong.. a lot of my younger days learning how to shoot were with open iron sights, and learned to shoot targets with a double peep sight. Not really by choice, the guns I had weren't easy to put a scope on, and money was scarce too.
The biggest pitfalls to iron sights are, in order of appearance.. low light conditions that make it hard to see them and the target, they block out part of the target, and in my mind the worst one.. you can't easily see what's BEHIND the target. A clear view through a sharp scope will show you the target, what's around it and behind it, all that's blocked is the space the reticle takes up.
I have an old 32 Special model 94 Winchester with open iron sights I use once in a while, knowing when I leave the house that the gun has limitations. I still use it, but not often. If I'm going out early or late, or if it is likely to be a longer shot, I take a 270 Model 70 which has only a scope, no iron sights. If for some reason the scope gets damaged and I can't shoot, well that's life.
Not to rain on anyone's parade, but hunting using iron sights on a 30-06, 308, etc is a little bit like using stone broadheads on an arrow. I know there's a lot of folks that do, but if you can afford better the animal you're hunting deserves your best shot, literally.
For playing around, shooting steel or paper targets, iron sights are a lot of fun, makes things more competitive too.
My 2 cents,
Sean