You are very exposed out on the end of two lines in fast moving water. You are relying heavily on your belay team which can't hear you. Setting safety below is always a good idea. What if something goes wrong and your quick release is stuck? Sounds farfetched? Not exactly, something similar happened to a SWR instructor during a class on the Cheat Narrows a couple of years ago. He was on a zip line and his quick release belt failed to work correctly. If breathing OK, perhaps your belay team can get you quickly to shore. If not, this is where your rescue knife comes into play. You may need to cut the belt or tether. This is just one reason we always carry a rescue knife when working around ropes.