i've never used a sb die- but i accumulated a 223 that has the chamber cut so tight that my normal loads have a devil of a time chambering. Anybody use sb dies enough to determine whether or not they have any affect on accuracy??

I haven't found them to have a negative affect on accuracy.

I use SB dies on several rifles that have tight custom chambers. Used in those situations there isn't any accuracy penalty.

Using them when they aren't needed brings a quick death to brass.

Make sure that it is your chamber OD, and not the base to shoulder length, which is the problem 99 percent of the time. I have found that small base dies are rarely, if ever, needed. What is needed is a shorter die (which is easy to do), or a longer chamber, which is also easy but not as easy as trimming off the die.
Small base dies were develop;ed as a solution to a non existent problem. Or very rarely at least.