Tiles are (in my opinion) an abomination. I never learned to love them. In JSF, tiling can be done using the Facelets subsystem, which is available as an add-on for JSF1 and is an integral part of JSF2. So one reason to consider facelets is that unlike tiles, it's a part of the current JEE standard.
Regardless of what tiling system you use, however, you cannot update just part of a page (technical term: "partial page update") using straight HTTP. You need AJAX to do that. That is, in fact, exactly what AJAX was designed to do.
In JSF1, there is no built-in support for AJAX, although some of the third-party extension tagsets provide AJAX support that make it very easy to do partial page updates. In JSF2, ajax is additionally available as part of the core JSF JEE standard.
Customer surveys are for companies who didn't pay proper attention to begin with.
subject: Is it possible to reload only body in the tiles