iDRAC managed by multiple OMEs?

User_a,

If you are monitoring from multiple instances of OME that would be fine. However, for operational clarity and to avoid conflicts (especially with firmware baselines, alerts, or job queues), you would only want to manage from one OME instance., You are correct in the steps you listed, but you would also want to consider if the old OME had any baselines, alerts, or job queues configured, and configure them on the new one. 

Let me know if this helps.

And how do I accomplish a 'clean' device migration from OME to another?

Its not really a migration, unless you are going to change specific versions of OME, but if just an OME to same OME version then you can do a backup, install new OME and restore with tab highlighted below. 

Is the restore option possible when moving from a VMware based appliance to a HyperV based appliance?  I was trying that approach, but my VMware based appliance backups do not appear when trying to restore to the HyperV based appliance and the AI bots seem to indicate that it isn't possible although I can't find the Dell docs stating that.  I would prefer to not have to build everything out on the new install if possible.  I am also using the vCenter plugin and wasn't sure how to properly migrate that setup to the new install.

Hello,

No, you cannot restore a VMware-based OME backup to a Hyper-V appliance Dell only supports restore on the same hypervisor type.

For migration, you’ll need to deploy a new Hyper-V appliance, manually reconfigure settings, and reinstall/re-register the vCenter plug-in.

Thanks