you should implement this on your custom firmware.
That won't do any good, since most people move from stock to my firmware, so they will still be set with their USB 3.0 port running at USB 2.0 speed.
This trend can be seen by the number of folks going from stock FW to my FW, and wondering why their OpenVPN server is suddenly enabled - that's because Asus changed the way one of the OpenVPN nvram setting worked, effectively breaking compatibility with my firmware. I'm currently not really hot to the idea of having to change to a different nvram setting, and then have to deal with all the users wondering why their OpenVPN is suddenly NOT enabled anymore, as they failed to read the changelog.