Caveat, I don't have a C8-Pro or Hue Bridge Pro.... 
I would expect so, given that you can have multiple hubs / platforms connecting to the HE hub API. Regardless, another option would be to connect the Hue bridge to one HE hub and then use Hub mesh to provide access to another HE hub.
Thanks!
I am fully aware of the mesh option, but for clarity and speed I would rather avoid it.
The reason for this exercise is freeing up one lan port and one zigbee channel.
I'm not sure I understand entirely....
Freeing up a Zigbee channel could be achieved by pairing your Hue devices directly to one of your HE hubs... (EDIT - Or technically having a net effect of no increase, if you do not already have Zigbee enabled on one of your HE hubs). Having both HE hubs able to communicate with the Hue Bridge does not do anything to relieve you of the Zigbee channels in use, unless I am missing something...
For your LAN, I presume you mean that one or both of your HE hubs is connected to your LAN via Wi-Fi, rather than an ethernet cable, which is what you are trying to limit use of? While I can't point to any testing results, I would not have thought Hub Mesh would load the HE hub up any more than using the Hue API, more likely the API would be more resource intensive... Again, I could be missing something here....
I should emphasise though, I think the answer is essentially yes to your question, you can setup multiple HE hubs with the Hue Integration.
Maybe I am not to clear.
Got two C8's and two Hue Hubs old style.
Each linked together, controlling each end of the house. It might be overkill, but I do have more than 350 devices.
Having a fully loaded 24 port switch, I saw the possibility to free up one port by only have one Hue hub, I don't really like wifi if it can be avoided.
It would also give me a free channel for zigbee since also that part of my setup is stretched to the limit.
I have (maybe two years ago) tried running bulbs directly to the HE, but the performance was really lousy, I then was advised to run through a Philips hub, which works well, the very best would of cause be running directly to HE
It shouldn’t be a problem connecting a Hue bridge to 2 HE hubs. I also have 2 Hue bridges and am just waiting for the Bridge Pro to be back in stock so I can consolidate my 2 bridges.
So you are intending to replace the two older Hue hubs with a new pro version? If so, depending on other things you may want from the Hue pro-version, would another switch not be cheaper? Plus, if you are already at capacity, you are likely to want a new, larger switch sometime soon anyway...
But with your explanation, what you described at the beginning now makes more sense, thanks for clarifying the detail.
With that many devices I would imagine the migration to HE and testing of the setup could be a time-consuming exercise, even if things have improved in the last few years and there could be other reasons for the poor performance. The only other thing to consider is the number of devices on the one Zigbee network could become problematic, regardless of the lift in devices the hub can handle.
I am using Unifi and that is not cheap, a pro Hub is cheaper
I do not have any big issues, and yes, it will be a rather big job to move it all.
I am now in the process of migrating.
It can be done, but it did not bring over the names for one Hue hub, meaning they have to be located manually, renamed and added to the broken rules where they belong.
I migrated 2 Hue bridges to the new Hue bridge pro a few weeks ago and am very happy with the performance. I also migrated my main Hubitat C-8 to a C-8 Pro the same week. Both went very smoothly. Glad I didn’t wait for the update to be able to automatically bring over the second Hue bridge, since it sounds like it wasn’t a very helpful feature. It was fairly painless to gradually delete devices from my second Hue bridge, add them to the Hue bridge pro, add them to Hubitat, and patch the rules. I don’t think I would have enjoyed doing it all at once.
