How many gallons is your tank? That is the biggest factor for the survival of the peppermints or any other ornamental shrimp with a coral banded shrimp.
I have two cleaners, 2 sexy shrimp, 2 anemone shrimp, 1 peppermint (though I used to have two until one died of age). all in a 46 gallon. I wouldn't add 3 peppermints with a coral banded shrimp in a tank smaller than around 35 gallons. 30 gallons is ok, but its kind of a stretch, one of the pepps is likely to get eaten. You could keep one or maybe two in a 30 with one.
If you have larger than a 35 gal, go for it than, its perfectly ok.