I gave it a try and couldn't get it to change. It will show as the new address in the terminal window but when I hit option + wifi it shows me the prior address.

I am actually suprised this was possible even in Mavericks. Using it since then...

Yes UI shows original address and existing connection will use existing address (ie not changed) But if you re-connect (turn off then on WiFi) it will use new one.

Weirdly "disconnect" was always using whatever set in the ifconfig. Meaning that I could "deauthenticate" other people by spoofing their address.