I always use a SB die just in case. No issues so far
I use small base dies as well & have loaded thousands of rounds for multiple guns with no issues whatsoever.
It just so happened that when I needed FL dies, that was all that was available so I've used them for years.
I have a body die & a neck sizer that I use for my bolt guns.
But the SB dies used for loading for an AR, while probably not necessary for most guns/brass, hurts nothing at all. The small amount of extra sizing near the base cause no real shortening of the case life.
One the other hand, it will ensure that your sized brass will chamber, assuming you also get the HS right as well & don't leave the case HS too long for a given gun.
MM