I am generally very happy with my HE C8 (and C7 before that). I am pretty capable of adding devices, writting Rules, etc. The biggest problem I have is with deleting devices. I have experienced more problems with deleting devices than anything else I have done with HE.
There can be "dead" devices. And there can be "working" devices that I just want to replace with another. I have used the "Swap Apps Device" and it is great; possibly the greatest addition ever made to the HE!!!! But even using the Swap Apps Device, you may still need to delete the old working device after you have swapped it for the new device. And this is where I have regular problems. Though... this may be more of a problem with non Plus ZWave devices.
I have learned to physically move the device to be deleted close to the HE before I try to delete it. But even then, PROBLEMS.
I just replaced 3 identical old and functioning (non ZWave Plus) devices with similar ZWave Plus devices. Adding the new devices worked great. Using the Swap Apps Device to swap the old device for the new device worked great. But when I tried to delete the 3 old devices from the Devices screen, only 1 out of the 3 old devices properly deleted. The other 2 devices did not, and HE asked me to "force" delete the devices, which resulted in them being deleted as a device but kept them in the ZWave table. At that point, you have to screw around with the ZWave Details screen hoping you can delete it without leaving a ghost device. This is problematic as you have to remember the non-obvious sequence of hitting the "refresh" or "repair" or " discover" sequence to delete the device from the ZWave table. NOTE. Once you try to delete a device and it does not work, and it asks you to Force Delete the device, you can not retry to just delete the device, again. If you Cancel the delete process and try to delete the device again, it takes you again, to the Force Delete. Perhaps this whole problem would be mute if you could just Cancel the delete, leaving the device in the Device Table, and try to the whole delete process, again.
I would suggest and request that when you try to delete a ZWave device, no matter where within HE you try to do so, the Devices screen or the ZWave Details screen, that it take you to the same single screen that then holds your hand and walks you through the entire device delete process. Provide lots of textual description of what you are supposed to do. And if it gets to the point of Force Delete the device, it then takes care of doing whatever needs to be done in the ZWave Details screen to properly (or as best it can) also delete the device there. And if it results in a ghost device, it should know that and tell you that you have a ghost device in the ZWave table and suggest/direct you to instructions on how to delete a ghost device.