I have been using SP for about a month now.
It mostly works, including most gas stations but one usually has to do the trick where you insert non-mag card into reader to "turn it on" as you get blank card fully inserted bring the already broadcasting SP close to reader then pull out blank card.
Yesterday tried SP at an HD for first time.
Tried two Raw/ogranic/normal SP attempts.
Both rejected.
Tried the blank non-mag insert trick.
That worked!, SP went right through.
It would be great if someone can confirm if this works for them too (or not).