I have used three USB-C displays extensively: a Dell U3219Q, an LG 27ud88 and an LG 32ud89. The 32" Dell and 27" LG work flawlessly: usb ethernet dongle, usb ss

I have used three USB-C displays extensively: a Dell U3219Q, an LG 27ud88 and an LG 32ud89. The 32" Dell and 27" LG work flawlessly: usb ethernet dongle, usb ssd drives, USB audio interface, mouse and keyboard work great. They don't even crap out on sleep/suspend. My LG 32UD89 has been rubbish though, it needs to be powered on before the macbook wakes up or it needs a hard power cycle to detect USB-C input. They are all very pricey though.