few things to note here:
in terms absolute speed, firewire 800 is faster than gigabit networking in the real world, in the same way firewire 400 is faster than USB2 - it's all due to bus speeds.
networks have loads of overheads, USB2's bus is too narrow for using as a scratch disk, and unless you're going for Fibre Optic networking, you're better off forgetting it unless all you store is MS Word files.
i did have more to say but i forgot. sorry. 🙄