With export, you cannot select manually content items to sync, there is only one option - sync everything, and if there will be an error during the process of import it will terminate the process and it would be hard to tell what was or wasn't imported.
With content sync tasks there is never gonna be a one-click magic button that will do everything nicely for you. That's why I believe it is easier to do it via Staging rather than an import. With Staging you can sync section by section, and therefore deal with sync errors on a smaller chunk of objects, e.g. page types first, then web parts, then content, then something else depending on what are you using within the system.