I think you have a migration tool inside the ePO 5 package so you can migrate from a server with ePO 4.6 to a differente server with ePO 5.0 on an easy way
Moving everything (i.e. physical machine, ePO and Sql version) requires a little more effort.
It would go something like this:
1. Make a disaster recovery dataset of the old server as described in McAfee support article KB66616 (assuming this is not a cluster. Cluster DR is a slightly different KB article).
2. Build the new server with a supported Sql version for ePO 5.0.
3. Install a clean copy of ePO 4.6.6 on the new server.
4. Do the disaster recover restore on the new server using the info gathered in (1) and the same KB article.
5. Check the newly restored ePO 4.6.6 is working ok and managing the existing clients as expected.
6. Only then upgrade the news server from ePO 4.6.6 to 5.0 using the migration tool as described in the ePO 5.0 installation guide.
Don't decommision the old server until the new server is known to be running ok so you have a fallback position.
Has to be done like this as you can't migrate the ePO DB to a new version and new server at the same time, and you can't upgrade the old server since it's running an unsupported Sql for ePO 5.0
Many thanks for the feedback - I will try this.
Did you try following rackroyd's procedure? Any luck?