If you have an HUSBZB-1 on your C-4, which does both Zigbee and Z-Wave (unless you have a second external Z-Wave stick, e.g., in non-North-American markets; the C-4 has no built-in radios, so if you have devices of both protocols, you have something for each), you can move that over to your new hub. Coupled with your hub backup, that should cover both your Zigbee and Z-Wave devices. (That being said, I had bad luck moving a Z-Stick between two hubs once, which should have been easy...not sure if that was bad luck on my part. They were different models, a C-5 to a C-3. I ended up just redoing all of those.)
In the absence of doing that, you can just restore the hub database. Resetting and re-pairing your Zigbee devices to the new hub with the database will cause the hub to recognize them and slide them back into the same "device" they were before. This means you won't have to redo any apps/rules (except Groups and Scenes; go into any group and click "Done," since resetting a Zigbee bulb/plug will also erase its internal knowledge of what Zigbee group IDs it belongs to). In my experience, this is pretty easy--I did that instead of moving the stick from my old hub when I got a C-5. Your level of patience may vary depending on exactly how many devices you have and how easy they are to reset.
May I please ask why? I personally believe the C3/C4 hubs have had fewer issues reported than the C5 hubs (especially considering the C5's network interface issues.) The CPU power, RAM, and storage are the same on both hubs.
I have a C3 as my main Hub (Zigbee, Z-Wave, and Lutron devices), a C4 as an auxiliary hub (mostly cloud integrations), and a C5 hub that I use as my development hub. This has worked very well for my needs.
The NIC in the C5 hub has had issues with auto-negotiation of speed/duplex for some users' network hardware. Hubitat implemented an automatic fix for this that takes effect within 24 hours of the hub detecting it. There has also been at least one user who determined his C5 hub was generating CRC errors. This was corrected by the Hubitat team via a replacement hub. I have never heard of anyone experiencing these issues with the C3/C4 hubs.
I have a C4 Hub that has the same problems as @TechMedX and thinking of changing everything to the C-5. Last evening I had to restart the hub numerous times before it came online. @bertabcd1234 You were saying that I can back up the hub database to the new hub?? Did I read that correctly?
I’m not certain we can just look to the hub on this one. C5 hubs came out at around the same time as Lowe’s closed down Iris and it has been the hub available for migrating Wink users. Few came over prior to the release of the C-5.
Don’t get me wrong, I’m not blaming these users, but the nature of the systems they were used to left them in the dark about a lot of the techniques, procedures and experience that many who came on board from SmartThings at the time of the C-3 and C-4 hubs already possessed.
I’ve also noticed that many in this thread and on the forum that have multiple C-5 hub with no issues, are also more experienced with the technical knowledge and finesse you sometimes need to get a ton of Z-Wave and Zigbee devices to play nice together.