Hello Rusty,
Users at the remote only suggest and give direction, but at end of the story everyone has to make it by himself.
I am not saying your immediatly migrate the VMs and do upgrade. You can do in steps like add both the hosts in vCenter and one by one, you can migrate VMs. It will give you enough time to plan and migrate and then you may plan for upgrade to next level.
Regards,
Sachchidanand
