USB 2.0 480 and firewire 400 are just nominal maximum figures.
And you have firewire 800 that can go "up to" 800.
Be aware of USB if you share the ports, as each device will share the the 400 you have got. An pay attention if your controller is driving also USB 1 devices, as all will slow down.
USB doesn't transmit the signal in a continuos way and is the buffer that gives you the illusion. Most times is ok, but not for video for instance. It can cope or not, you take the chance.
Firewire does it in a different way, that's why digital video capturing was a firewire business (now USB is doing, but look they do it with MPEG not DV signal).
Firewire depends on chipset. A good one being Oxford 911, but sometimes the name you see is the one that made the board or sold the electronics to it, not the chipset maker.
By experience with hard drives, taking the same big file firewire was faster that USB on a consistan way. But this is just one experience and opinion.
And don't believe in 60 or 50 MBs/sec, thats not the real world....