Neither of those is designed to interface with Final Cut Pro. They talk about ProTools, Logic or Garage Band compatibility but I don't not know if FCP can route multi channel audio via either of these boxes.
MOTU makes an interface for FCP that can handle both picture and multi channel sound.
http://www.motu.com/video . If you want to experiment with devices that are not designed for FCP, then bear in mind that they may not sync with your pictures even if they work. Also bear in mind that FCP cannot do surround panning, just direct routing of channels.