Migrating Multiserver Setup to New Machines

Hi,
since my ISPconfig managed machines have aged somewhat, I am trying to gradually replace them with new ones (esp. since there are some major issues with upgrading Debian 10 to 11 and higher in-place, and generally my VMs are on an outdated platform anyway so I should go for new ones).
My idea was:
- replace Master node:
Set up the new machine, load backup files from old master for websites, email accounts and databases (including dbispconfig), then install ISPconfig updating the existing data and resync all local items on that node.
Tripwires: I want to move from Apache to NGINX in the process. The IP address of the master node is definitely going to change, but the DNS will be switched so the node name will remain the same.
Is this going to work? Am I missing something obvious?
Then:
- replace Client nodes one by one as I move along:
Set up the new machine, load backup files from respective old node (as above), then resync.
Tripwires: _some_ nodes will move from Apache to NGINX but not all (as I have situations where Apache specifics are still required), IP addresses will change, DNS will be switched. Does ISPconfig need to know the actual IPs somewhere?
Is this a workable path? The only alternative I'm seeing is starting an entirely new setup and migrating the users one-by-one, which is pretty tedious and potentially even disruptive for affected users. I'd like to keep the impact minimal.
I may have asked this before, but setting up the new machine as a mirror of the old one and then switching the replica to master is unlikely to work if they use a different base system, correct?
Thanks a lot,
Gereon