For Duvel, the M41 is good, because it finishes really low. Use a combination of Pilsner malt, wheat malt and 10% white sugar (sucrose). This is for the colour. Bitter to 30-33 IBU with noble hops (or EKG).
The impression I got from Brugse Zot, is that it does not attenuate so low as Duvel, and...