We've got a group of parents around us who'd likewise like to delay their kids' smartphone access for as long as possible - but if a smartphone (or even a dumbphone with no meaningful parental controls) is the only way for kiddo to make calls, then I know some of them will defect. Selling them all on this kit (or something like it) would keep the agreement intact for a while longer.

For rsync, a person would have to study it to learn it. They might want to look for potential gotchas in how they configure it, too. The experts at Dropbox already did all that for us, though.