I have peppermints and have wanted to get a cleaner but I have read several posts that have said that cleaners often will go after and kill peppermints. Now of course there probably are plenty of people who havent experienced this but I have avoided adding additional shrimp because of it.

heh, if this tank is overstocked, mine is a mini Tokyo...

I don't even count my invertebrates when I think about stocking limits, unless they will blatantly fight.

I've got 4 cleaner's and 4 peppermint's living together. So far no problems with fighting, the peppermints are so nocturnal I only see them once or twice a week, but they always have egg clusters (as do the cleaners) so they can't be too stressed out.