Something worked surprisingly well for me. I have some computers connected to WiFi only (no LAN around) and I've started using a Comet Pro inline with the primary monitor and connected to the Ethernet port on the PC. The end result is that I can connect to the Comet via WiFi and the hardwire Ethernet port doesn't get an IP address but still send WoL packets - allowing me to wake the connected PC (awesome!).
The only downside is that the display shows the dummy IP from the LAN interface (169.whatever) instead of the WiFi interface IP. Since I have a hostname properly configured this isn't an issue, but it would be nice if it wouldn't show an IP address without connectivity if one with connectivity is available.