Hey Josh,
I have my Vivint Sky Control Panel connected to my SmartThings hub as a secondary controller. It didn’t work very well at first, but my firmware has been updated several times since then. Today I installed a new Kwickset Smart Lock and when I associated it to my Vivint Panel it immediately showed up in my SmartHub too. All of my switches that are associated to my SmartHub are now showing up on my Vivint Panel. I can control any device from either place!
One thing to note is that I am part of Vivint’s Beta program so I don’t know if the (working) secondary controller functionality is public yet.
Give it a try and let me know if it works for you. If not, you might just need to be a little patient until the latest firmware comes out.