So while trying to resolve a problem with the dock USB3 ports operating at USB2 speeds I unintentionally solved a problem I'd had with Win 10 not activating from a clean install after a successful in place upgrade. Can't believe I didn't twig to this earlier but when I did the in place upgrade to Win 10 I did it while connected to the dock. Then when I did a clean install later with my SP3 undocked Win 10 refused to activate. It is seeing different hardware from the initial in place upgrade so refused to activate. I can see this might end up being a real pain for people who either sell their dock or their SP3 to someone without the dock the upgrade was done with.