The zwave network has been great for 10 years - only since Christmas has it ever shown any issues, which coincided with the migration to HE.
Could be a coincidence.
But having 100+ zwave devices with 80+% being mains powered I would expect it to be solid.
Certainly the devices all work Ok, and are reporting nicely, only the Including element is messing up, if you included the barrage of Ghost Devices created by including a device.
So I agree with you, would have stayed with a v5 zwave, but did not see that as an option on 24 Dec.
I have onboarded a lot of devices since Christmas, certainly the Inclusion process has be very clunky indeed, and as they were included 2 ft from the HE Hub don't believe the zwave network quality was a contributing factor in the inherent unreliability and subsequent spawning of ghost devices that require 20+ Remove attempts and hub reboots before they finally go.
These devices, being v7 devices are the absolute worst devices to connect to Hubitat to date and that is a tough one to win, with so much competition for that title.
The Aeotec seems incredibly well built and it is surprising to find them so bad.
I am left leaning towards the issue being HE c7 rather than the device, given that the SiLabs 700 fw bug is causing so many issues inside HE to make HE appear just confused - adding through SMARTSTART once results in 4 Devices showing - ALL OF which fail to include.
Also, the way that you have to press REMOVE so, so very many times to get a ghost device to die.