Hi Andrew,
Has anyone looked into version compatibility between the different versions of sqlite? For example, on the same ISP, one server I checked has sqlite2, the other has sqlite3. Neither server has both drivers installed. Neither server actually has the sqlite binaries installed, though I assume that isn't common, but worth checking on other SQLite supporting hosts.
The SQLite site mentions using the command line tools to dump and restore the DB, and I haven't found anything about doing that from pure PHP. This probably wouldn't be an issue for caches and such, since an incompatible DB can just be recreated. I could see it causing headaches for "Drupal Lite" scenarios.