Thanks Pete. This was exactly the information for which I was looking.
In my haste I neglected to mention that I was specifically trying to determine which option yielded the most thorough scan (particularly when using, or not using, forced demigration). However, from what you posted above, my question was still answered in it's entirely anyway.
It appears the most thorough option is scanning them all without forced demigration (since the demigration might possibly cause some files to be skipped).
Thanks again for replying.