Here's my expereience with pipefish.. keep in mind I am not an expert on them! This is just kinda what I've observed with mine over the years.
I have tried 2 different kinds of, the banded and the dragonface pipefish. The banded pipefish had a hard time swimming in my Mixed Reef because the flow was just too high for him in my opinion. They seem to be more open water swimmers like fish except they seem to prefer calmer spots. The one I had swam around a bit but then would retreat to the calmest part of the tank that he could find. Anyway, he didn't last beyond a month, maybe two. Never ate anything but pods.
I have a dragonface pipefish that I've had for a couple of years and two more that I added after that I've had for about a year now. The dragonface pipefish is quite different in that it doesn't really swim around at all. It mostly slinks around through the rocks and corals hunting for food. Because of this he is fine in a high flow reef tank. I never see him/her swim. Even after two years my pipefish never eats frozen, or at least I never noticed if he/she did. Strictly pods which I have an abundance of. There was a period of a few months this year where I didn't have any coral in my tank at all and all 3 of my pipefish did fine hunting pods and such. Another point to make is that they are quite social. When I added an additional 2 pipefish the 3 of them immediately found each other and like to hang out together. I have not noticed any aggression from the 3 of them at all. They always sleep together. I have never seen any of my fish bother the pipefish.
Hope that helps!