I've tried peppermints dozens of times over the years and have never had any that would eat aiptasia ... maybe I have a different aiptasia or maybe I keep getting the wrong kind of peppermints .. there are 2-3 Lysmata sp. peppermints that look nearly identical, so who knows. Anyhow although some people have better luck with these things, I never have had luck with them, just my $0.02. They are interesting shrimp and they breed if you have 2 or more, which give your fish and everything else that feeds on plankton, a nice infusion of live food ....
So that's kind of a nice benefit. Although you'd get the same benefit with cleaners - just need 2 or more.