While on the subject of carp flies, I've had them take P&Os in moving water but I've never had the same success in stillwater. My only stillwater hookups have been when I've targeting smallies and ended up with a golden bone peeling line instead.
Once in a while, I'd be able to get back to where I fished as a kid. There's this small bay on the St. Lawrence that holds huge pods of carp. I'd use an 8 wt. to toss long a large bushy dry to one side of the pod. On each cast, one fish would detach itself from the pod, slowly cruise over, tilt up, inspect the fly, then circle back to the pod. I could usually get four or five fish to check out the fly until they lost interest altogether, but I could never get them to take. I've tried movement, no movement, nothing. They were interested though.