Which is why I said "usually", not "always". I'm faily sure that the Transit that I mentioned as an exception is also USB 1.1.
I guess full speed (12Mbps) is there for devices that don't actually need to use 480Mbps.
Those are the theoretical speeds but USB actually has a very high overhead, which is why Firewire (IEEE 1394) that is rated at 400Mbps is usually faster than USB 2.0. Maybe that's why devices like the Sonica or Transit only support 24-bit/96KHz when turning off duplex mode, even though a 24-bit/96KHz file takes up roughly 2.5Mbps.
Anyway, I'm not an expert on these things so if someone with more knowledge on these can enlighten us, please do.