I have had a lot of luck with delinquent clients when I explained that the title abstract was my property until they paid for it. I offered them the choice of paying for the search or returning it with all copies they made of it. By the time you demand payment they most likely have already used it to generate a title commitment. Then the fun begins. They really are not in a position to do anything other than pay you, or defend in an action for conversion (civil theft).

Insofar as a disclaimer is concerned you have to be careful of overkill. If you put too many restrictions on the abstract you may lose established clients, and discourage new potential clients. I think a simple statement should suffice that the abstract and information contained therein and gained from your labor remains your property until you are paid.