I once had an USB1.1 hdd, for backup. But it was too slow.
Firewire is fast enough to use it in a good way. It's faster than USB2.0 BTW. (Even though the transfer rate from USB2.0 is higher. But USB is very inefficent in transporting data, that'S why 400MBPS firewire is faster than 480MBPS USB).
If you have a DVCAM, you can copy your selfmade films to your hdd via firewire, that's what is probably mainly used for. On the DVCAM the firewireport is calle ILink!
You can also use firewire to build a network, BTW. I once did that with a friend.
Just a few other things you can do with firewire.
A hdd connected to firewire will defenitely be good and fast. So now worry's here.
For an external hdd you should probably buy a Firewire external box and the ide hdd. If you buy it already build together, you don't know what kind of hdd there is inside. So maybe it'S a cheap seagate one, which will break after 1 year. (my experience)
So build it yourself, that the best way to make sure that your backup is secure!

A380