If I update my llbl version, I have to re-generate all the code (both derived and base classes). But that implies that I'll loose all my custom business logic code in my derived classes? Do I really have to regenerate those files as well when switching from 2003 to 2004 version?
If your business logic is placed inside the derived entities in a two-class scenario, use the full/safe option to re-generate the code, which makes sure your classes aren't overwritten. The derived entity classes haven't changed.