Did you change FS type along the way?
Are you sure you cleanly stopped and quiesced the application properly before copying/re-mounting?
Can you show the exact commands that you used?
How did you verify the copy/rsync?
rsync -av does not copy hard-links, ACLs, extended attributes, sparse files (and maybe other properties and attributes too?). How did you prove that the target file-system structures and contents were exactly the same as source after copying?
And, I'm just curious (not that I am aware of any reason why they cannot be different), do both XFS file-systems have the same block size?