I agree with Bio; however, in theory a really good business strike could look nicer than a really bad SMS (late die state). The truly only guaranteed way to know you have an SMS is to get one from an OGP set. Anything else will always have the small chance of being wrong.
Quote: Interestingly I have seen SMS coins included in proof set runs on eBay. I would consider SMS coins proofs though.
I think it is a matter of personal preference. For what it is worth, the Dansco Kennedy half dollars "with proof only issues" album (8166) has places for the three SMS coins. It also has space for the 1964 proof, which was not a proof only year since a business strike 1964 exits as well. Yes, the 8166 is rather unique in those choices.