I've heard the same. The fancy ones listed on Biota supposedly have a better track record.Peppermint shrimp have always been more trouble than they are worth to me. Hit or (mostly) miss with aiptasia and tend to annoy your corals and clams as the try to steal food from them.
I haven't tried nudis yet as I have a few wrasses that would eat them and have had to go manual Kalk injections to eradicate with extreme prejudice those little jerks.