Deck to Hull fastening....
I don''t know how the Dufour deck is joined but the 40.7 has a pretty wide inward facing deck flange that is glued and bolted. According to one of the Farr guys they are using a high strength adhesive (not 5200) and then thru-bolting. Many of the better modern adhesives develop an stronger bond than even the secondary bond when glassing. So if the flanges are wide enough, you effectively do end up with a monocoque joint. In the case of the 40.7 the thru bolt heads are concealed below the toe rail.
I sail aboard a 40.7 that has been raced quite hard and has roughly 10,000 sea miles and still feels as stiff, and is as leak free as a new boat.