If you’re using a laptop, a smaller desktop computer without extra space to add more internal drives, or need to move footage often between systems, an external, portable firewire drive could be useful.
Unfortunately, at the time of this writing, external firewire drives are not 100% reliable when capturing video. But, if your external drive drops frames while capturing, you can always capture to the internal drive, then move it to the external drive for editing.
But having all your project media on the external drive means you can take your edit with you- work on your laptop at home, then bring the drive back to work and hook it to your big, fast desktop machine.
Every time I see a shooting star I wish that all problems with external FireWire drives would go away, so if your drive works great you may have the Perseid meteor shower to thank.
Until then, our advice is to only buy a firewire drive from a reputable company who allows returns without a restocking fee- that way you can test the drive thoroughly with all the systems you plan to use it with to make sure you’re happy with its performance.