@JDRoberts, yep, I’m well aware of the issues that can happen with WiFi and Zigbee. Unfortunately smart things doesn’t provide us a way to change the Zigbee channel. At least that’s what they’ve said here. My hub uses channel 15 so I’ve setup my router and AP to use WiFi channel 1 and channel 11 respectively with 20MHz bandwidth not 40MHz. That has pretty much eliminated any interference issues I might have had.
Here is a good article for WiFi-Zigbee channel coexistance for those interested.
You’re certainly right, the Z-wave version of the GE switch would be a cheaper option. It will probably only get cheaper since the Z-wave versions are sold by Lowe’s (and others) as part of their home automation. It’s likely that they are built in much larger volume.
I’m not sure why I have trouble with Z-wave to be honest. The lower 900MHz frequency should have less interference and in theory should travel better through the house. I think the problem is less about the RF connection and more about the maturity of the protocol. Zigbee is just a more tolerant protocol. Fortunately I’ve been able to mitigate the WiFi interference issues.