That is my understanding of it, if you are running 5.X you can migrate online and use the advanced option.
But here is another good article Migrating RDMs, and a question for RDM Users. | VMware vSphere Blog - VMware Blogs This articles goes into details different migrations scenarios and resulting outcome.
This is straight-forward process, as you have done already with others VMs, just make sure nothing is attached to the VM, even though this should not have impact on svmotion. Start with the standard svmotion to another datasore, if configuration files are still not migrated then use the advanced setting to confirm configuration files are migrated, just use the advanced option.
vfk