So, are all these drives USB only? It was sort of implied, but not stated specifically.
I have an Iomega eGo (though not the one in this review). I chose it not due to my fantastic experience of ZIP drives (I'm being sarcastic); but because it was one of the few bus powered portable drives on the market that offers Firewire 400 and 800 along side plain old USB 2.
Now, for most people, this may not be that important, but for anyone shifting large files around (DSLR photos and high bandwidth HD video in my case), then the sustained speed that Firewire can offer over USB (which is rather bursty) -- particularly in FW800 guise (nearly double the peak speed, and much higher sustained speed).
For those of us with higher end laptops (thus with FW400/800) with a need for high performance, you really can't beat Firewire. Well, until USB 3 becomes commonplace. Then we'll probably have FW3200 anyway...