I heard the coil whine on my unit several months ago for the first time and after that read the same on another forum. But for me it can only be heard in a very quiet room mostly at night and from no more than one meter from the unit. It's most audible when WiFi is used for high speed transfers.
I see another glitch with 10G ports. If the cable is plugged in and out several times (5-6 times) into any of the 10G ports, the port stops making a connection (LED is off too) and I have to reboot the router in order to recover from this situation.