using my N9 tablet, using wireless AC I got a FASTER speedtest than I did using my computer connected directly to my router. The difference is wireless AC is gigabit wifi and my N9 supports it. My computer doesn’t have a gigabit network interface.
When you use a USB network interface on a NP or a Mi, would it REALLY be faster than the native 802.11AC that they both support, providing of course your router supports it.