Dufour continues to build a fine quality boat today as they did in the 70's and 80's. If re-sale is a concern, just take a look on the popular web sites and review what they are selling for and how many Dufour boats are for sale around the world. Ask a broker to check what they have sold for as well and you will be impresssed.
On the East Coast, there is a large Dufour Dealer that just represents and services Dufour Sailboats covering a large chunck of the country.. They are a good bet to sell your boat for you as well at the appropiate time.