Does it make sense to simply copy the mysql\data files vs mysql replication between data centers? I am having the impression mysql replication might be complex when done cross data center. And if I just copy, I could easily switch to the other data center w/o worrying if it's primary or slave. Any thoughts?
MySQL with InnoDB storage engine uses multiversioning of the rows. This means there are changes to the database that may not be yet commited (and possibli will be reverted!). If you simply copy the files, you will end up in inconsistent state.
If you are using MyISAM, copying the files is safe. Replication hovewer will transfer only the changes, while copying will transfer the entire database each time. Which is not wise with large databases.