Switching to another (faster) bus won't necessarily improve anything. You have CPU overhead to contend with, as well as relatively slow I/O on the SD card. So, just because the port is moved to a faster bus and could support GbE, doesn't mean you would get GbE performance.
Your home network is likely already faster than the Pi can handle, let alone your internet speed. A file transfer across your network (scp a video to the SD cart for example) will already burst, then slow down as-is. You can see, the SD cart write i/o is the current bottleneck.
