The hit and miss with Peppermint Shrimp and aiptasia seems can be partly attributed to mis-identification.
The true Peppermint
L. wurdemanni (which eats aiptasia) is quite similar in looks to
L. rathbunae (which doesn't always develop a taste).
Though I've allowed (by neglect) the aiptasia to come back, I managed them before by the ones I could reach with Kalk paste (made with mysis juice) and with Peppermint shrimp the ones I couldn't. For some reason shrimp (Peppermint or Cleaners) don't seem to last in my tank more than a couple of month.
Here's one article on the two species.
http://www.reefs.org/library/article..._redfield.html