Object-oriented model vs. Relational model

Does the OpenAccess ORM allow to solve the topic problem? Usually the Business logic OOM is completely different from DB RM, when we develop the business logic we do this in the way of deriving classes, encapsulating fields, etc. When we design the relational model we always try to optimize by performance and size.

Example: in our OOM we can have the base class called Question and have multiple derived classes, which will have different behavior and extended properties for different question types.
In DB we can have either single table, which will have ALL fields for ALL question types or, as in our case, we have 8+ tables, which have relations to conform to 3rd normal form and be optimized by data amount.
The Relational and Object models in this case are completely different.

How such items are resolved by OpenAccess ORM?

Also, does OpenAccess ORM support selecting/adding/updating/removing data using stored procedures?
Also, what about properties in objects that are calculated? E.g. Question.isUsed property should return true in the case the Question was answered - currently we're solving this by having stored procedure returning us questions list and when someone is calling the isUsed property we use the lazy loading for refreshing this value if the question was cached for a long time or it is pre-populated by stored procedure on initial load.

Also, this is more to Telerik team, when do you think you will start PostgreSQL support?

Thank you very much for answers.

We'd be happy to use an Enterprise-level ORM and OpenAccess may be a very good candidate.

I am just starting myself, but ...

Please watch the two Jan videos
forward:
http://telerikwatch.com/2008/10/telerik-watch-minute-interview-with-jan.html
reverse:
http://telerikwatch.com/2008/11/telerik-watch-minute-openaccess-orm.html

DB RM is reverse with no collections, just start accessing...

OOM you will use the front end partial classes to establish the derived behaviors, if reverse or apply attributes if forward.

Stored Proc's is a good question.  I just did a quick look in the wizard and did not find anything.  So, per the manual, stored proc' are access using OQL.