Just have to position the antennae correctly
Good to hear. I have purchased a C-8 Pro T. I am planning to use my current C-8 for Zigbee and the C-8 Pro T for Z-wave and Thread. I need to do more research on whether a hub mesh will add functionality to the hubs. Hope it works like I envision it!
If you mean the Hub Mesh feature on the Hubitat hubs, it doesn't add functionality, but does allow you to share devices seamlessly between your hubs. I have a C8-Pro that does all of my Z-Wave and some Zigbee, a C7 that does Zigbee only, and I share Zigbee devices from my C7 to my C8 so that I can create automations that use all my devices on the C8-Pro and C7. (I actually have more hubs, but simplifying to offer an easy example of using Hub Mesh.) So you'll be able to share your devices between your C8 Pro T and C8 however you wish.
Let’s put some qualification on that. As far as I know, the web interface is used now, but the mobile app is to be determined. I know there are limitations at present but won’t try to detail them as I don’t know with confidence.
Also, device firmware upgrades currently require a different TBR.
I'll stand by my answer, but also see your caveat thread-ers. 
My C-8 T is going to be delivered tomorrow. I'm about to find out how it all works out.
The years-long home automation adventure is a delightful hobby, occasionally appreciated and well tolerated by my wife. A few hundred assorted devices and some somewhat complex automations. BUT, I'm not sufficiently bored or rabidly curious to jump down the thread matter rabbit hole just yet.
Watching with interest.......
I don't think @Dangerous_EE means this. It's been talked about on multiple platforms and they all say the same as you, it's not good and not recommended.
looks like he came back to explain. I have the same understanding.
I agree although they would not want to do this, remember their target audience. Just changing it over on a setting would be a support nightmare when people flipped it to "test" it and lost everything. Now what it should be is, a single bit to determine the mode but it should only be done on a factory reset hub.
The issue then though is restoring, how do they handle people wanting to restore their hub but only z-wave etc and all those edge cases. My guess is that this was one of the "technical" problems.
also another valid reason related to mine above.
Also they did have some issues when bootloading their z-wave and bricking hubs, so they probably don't want to run more risks here.
It does mean though that when the next HW of the hub does get designed, i would hazard a guess that this will be one of the improvements they make. Better bootloaders, ensure that the radios get rebooted on hub reboot etc.
Seeing there are 40+ more posts after this one, doesn't seem to be dead enough.
It's a cockroach topic...can't be killed.
At the same time, we did find out the technical reasons for TBR version of Hubitat. As non-EE, but technical person, it was nice to know.
Ok, so NOW is the thread dead enough?