Upgrade to v9 HA

So I'm tired of waiting for version 9 to be ready on my HA systems.

What is the correct way to break the HA and update from 8 to 9?

Should I simply turn off the slave units and then break the HA via the master?

Then do the normal upgrade path?

What is my fail safe / fall back?

I wish I could continue to wait but my bosses feel we have a business case to upgrade (HTML5 VPN / app access)

As always, thank you for your time.

-Jayson