Foam inserts are good for what they are intended for. Getting you through a race without the possibility of a flat. They are expensive, wear quickly because of heat and take some muscle to mount. I run Bridgestone ultra heavy duty tubes in PA rocks and haven't gotten a flat yet.
If you absolutely cannot afford a flat, then foam is the way to go, otherwise ultra heavy duty tubes work well.
Scott Summers Racing (I think that's who it is) is working on the next new thing. Many individual inflateable air balls instead of a tube. You flatten one or a few and you still have an inflated tire. The first prototype used tennis balls. I just went looking for a link, but came up empty. Maybe I dreamt it.