RE: Iron sites with a scope
Yes but not drastically, it does take some getting used to if you've never used them. In a charge situation I think that it would happen so fast that you would probably go for the quickest shot you'll have and that will probably be what ever you get to first and if not probably an off hand shot. I have yet to be charged and really don't want to be but I carry a 12 gauge pump just for such an occasion.
As timbercruiser stated you can shoot very close with a scope, your bullet will not jump much in the first 0-25 yards (nor have reached its twist to velocity rate) but it will be lethal just the same...