Lost of folks use/edit with USB drives, but what kind of USB port is in your computer? A USB3 drive on a USB2 port is going to work at USB 2 rates and simplex protocol.
FW800 was designed with storage media in mind, where USB shoehorns storage data in a less than optimum protocol. So My long time experience is FW800 will be faster and much less troublesome than USB. I've never found editing HD video thats on a USB drive satisfying, but you can get by with it.
If your computer is USB3, then the difference is not much. Editing requires some back/forth movement of data which USB is nor that good at.
Editing using Thunderbolt or USBC seem to be much more seamless.
But its one of those, it may be good enough for you things. USB drives are probably cheap enough that you can try it and see if you like it. There are some USB drives that don't comply with USB standards and won't work well with a Mac.
The workflow should be identical, regardless.