Just pulled the trigger on HE this last weekend. Arrived today and I was able to exclude all my Z-Wave devices and remove all the Zigbee devices from ST fairly quickly, then add them to HE. With the exception of one GoControl lamp dimmer that won't go into inclusion mode, everything was seamless.
The only struggle I had was finding out how to integrate with Google Home, but that was more a moment of forgetting how to navigate Google's menus more than anything else.
With Google Home my wife can still voice control the lights connected to the Lutron SmartBridge (pro arrives next week so no local processing yet).
The only thing I am missing is a native android App with functional presence sensor, but coming from ST, the Android presence sensor never worked consistently across 3 different phones. I guess what I want is easy, consistent, no fuss or hassle presence functionality, like an Android app that on connect grabs the WiFi AP MAC address and if it matches your home AP, cross references other location data from the phone and can update to "present".
Otherwise this is a fantastic product, more responsive than ST could ever hope to be and if you have futzed around with ST for 3 years trying to keep things working, the basics of HE should not be intimidating.
Bravo, cannot wait to see where it goes from here. Will be selling the migration to all the other home automation nerds in my social sphere.