Making IPv6 stick (and unstick) in OS X Sierra

I've been using IPv6 for approximately 4 years now and about 50% of my traffic goes over the tunnel courtesy of Hurricane Electric.

One of my token annoyances since going all Mac is the IPv6 setting didn't seem to stick across reboots or sleep cycles.  I seem to have found the solution, courtesy of this blog post

For Wi-Fi:
networksetup -setv6automatic Wi-Fi

For Ethernet:
networksetup -setv6automatic Ethernet

For a MacBook with a Thunderbolt Adapter:
networksetup -setv6automatic "Thunderbolt Ethernet"

To go back to disabling it, change -setv6automatic  to -setv6off.