The Dygma keyboards use sculpted keycaps (Cherry profile on the Defy, OEM on the Raise), meaning you can move the keycaps inside the same row, but moving them to another row won't work because the shape of the keycaps (the profile) is different for each row. 
As you can see in the picture, each row has a different side profile. If you change your keycaps around, your fingers will bump into different heights, which will be very uncomfortable.
Instead, you can purchase your keyboards with Dash keycaps:
This way, you can use any key layout you want without having to re-arrange your keycaps every time 😊
Alternatively, you can order a flat profile keycaps such as MDA or XDA, Colemak or Dvorak keycaps from another online shop and place them onto your keyboard.