Stephen,

Have you showed the useras that combos DO NOT require a mouse. They can type and press enter or tab to move on. You do haver to turn on the IncrementalSearch property, but that's all it takes.

As to alternative design. One method that is often used with rapid data entry situations is to suspend all validation until the user is finished entering data. Then post process all teh data they entered and validate it producing an exception table of any record that failed validation. Present the user with teh exceptions, adn let them fix these qwith data validation going on immediately in the UI. Once the user says they are finished with the exceptions you can then post everything that passed the validation to the data base tables.

When using this approach it is a good idea to provide the user a way to cancel the entire batch, to save the batch and its exceptions for later review, and/or if possible to post part of the batch and save the rest for later review.