Wow...had a crash. Had to reboot and latest version not there. went to movies folder and opened previous latest version and they I have NO IDEA what happened next but it seemed to create a new event somewhere and every time I shit down and relaunched FCPX it opened the version selected in Backups which turned out not to be the correct version.
This could be more intuitive I think.
I certainly think I would prefer the backups folder to be on the same drive as the Library on which the original is stored.