A buyer with 30% down is not necessarily better than one with 20% down and a seller needs to be properly educated regarding that particularly in these tough financing times. When the creditworthiness of the buyer is evaluated by the lender they are also looking at credit scores, long term job stability, profession, source of down payment and a cash reserve position remaining after closing.
As a former underwriter, I can tell you that I have seen many strong// buyers with less down payment. An agent who really knows the business is able to communicated the nuances of what makes a strong deal to a seller and help them intelligently make a informed decision as to which deal is truly in their best interest.
Education is power.