One issue we also face is we change the structure of our database with almost every release. We keep tabs on our structure with meta tables that are updated every time you stat the application and so our query engine can pick up the added/deleted tables/columns at runtime and we don't have to change any code in our queries. So we don't modify any classes or prog files. If you put code in an object that code will have to be re-written unless you have an extensive system in place to catch those changes and offer them to the user without you having to re-write classes and progs all over the place.