Back in the early days of Linux, the changes to the operating system were so dramatic that even when updating withing the same distro, in-place point release updates were problematic enough and it was always recommended that a major version release be done from scratch. There were just too many major changes to the underlying subsystems and package naming conventions. Doing an in-place update was just asking for trouble.
Modern distros have matured quite a bit even though there are occasionally some major subsystem changes being made. Yet it's never been easier to do an in-place major version upgrade.
I just did the upgrade on several Mageia5 systems and the results were consistent and satisfactory, not to mention simple.
Always backup critical information. Have a Mageia5 recovery disc on hand.
You can always download an ISO image to do the upgrade rather than do an in-place installation if your Internet connection is slow. DO NOT attempt an upgrade from the Live ISO image as it will overwrite your existing system.