I think that there should be a "use with caution" associated w/ all "reef safe" inverts. They're scavengers, which means they will find what they want to eat.
I have not had any issues with peppermints eating corals, but they also did not remove the aiptasia. It is not a guarantee that they will eat it. I did have a skunk cleaner shrimp eat a mushroom and a feather duster and I've owned two emerald crabs that ate zoanthids so nothing is 100% reef safe. If you have small aiptasias, you should be okay, but the question is, "What will the get a taste for once they eradicate the aiptasia?"
All that being said, I do personally believe peppermints to be a valuable addition to a CUC. I think often people are sold camel shrimp instead of peppermints and this is what causes the problem. I've seen LFS selling "peppermints" that were actually camels.