I don't know if you'll run into permission issues in moving those items like config files and spool files (probably not), but you'd need to make sure that all the items are the same between your machine and the centos machine (again, both are Red Hat based, so you probably wouldn't have trouble).
If you're using a virtual machine based on VMWare, I'd propose using the VMWare converter to virtualize your physical machine. I don't know if it's feasible for your purposes, but I've converted more than one working server into a virtual machine just so I wouldn't have to deal with migration headaches. I then just dealt with changing the IP address, machine name, things like that rather than the sometimes more hairy issues involving migration of users in a database or mail spool. I figured the downtime in converting IP addresses and installing VMWare tweaks would be less than potential downtime from untangling spool/permission/lost files/etc. issues in moving from Machine A to Machine B.
Sometimes altering the machines network config has fewer gotcha's than playing with all the interactions of mail systems with their validations, authentications, and spool issues :-)