I'm keeping cherry shrimp in with my CPD's -- the adult shrimp seem to be safe but I'm no longer seeing any cherry shrimp offspring - so I'm assuming the CPD's are eating them (I used to get alot of shrimp larvae in this tank).
The CPD's are breeding for me, so I'm pretty sure a change in water quality (etc) isn't the reason the little shrimps are gone...
It possible that the CPD's are sneaking a few adult soft-shelled shrimp right after they molt, I didn't count adults before I put the CPD's in there.