It shouldn't matter whether it's ESX or ESXi, as long as the target host(s) can handle the VM's configuration, i.e. virtual hardware version.
You can certainly also use VMware Converter. I mentioned backup&restore because you said the hosts are in different datacenters, so I assumed low bandwidth!? Keep in mind that VMware Converter may assign new UUID's an MAC addresses to the VM's and you may need to do some reconfiguration after conversion.
André