It's only 10/100 Ethernet, I can't see it being limited too much by the Bus speed. I've tested an apple-branded USB 10/100 Ethernet adapter at ~98Mbit on a beaglebone.
Right. USB 2.0 is already packetized with a MTU larger than ethernet already. The net overhead for the USB stack is near zero. It's true that fancy ethernet devices can do things like TCP or encryption offload, scatter-gather DMA for zero-copy transfers, etc... And clearly this isn't going to do that stuff. But if all you want is to get packets on and off the wire, there's nothing wrond with USB 2.0 Hi-Speed.
(FWIW: that apple-branded adapter is almost certainly an ASIX part -- the same chipset is sold under dozens of brands and works quite well in my experience.)
