I.e. the `UPDATE ... from ... JOIN` syntax allows to modify only some columns, while the `REPLACE INTO ... SELECT` forces you to select and replace all columns? That's the main benefit? Would be nice indeed. Isn't `REPLACE` equivalent to a `DELETE` followed by an `INSERT`, potentially also breaking cascading Foreign Keys as a side-effect, while UPDATE wouldn't? Would be a doubly-nice to avoid that pitfall, assuming I'm right above.