Inkscape can do the conversion from svg to dxf sometimes, but at other times, it crashed on my Mac. I've tried an online conversion service which seems to work. However, I cannot imagine the trouble of doing the conversion when testing design. I use a CAD program (TurboCAD) usually, but it has very poor text support. The design is used to drive a laser cutter. Often, the output needs to be modified many times before the desired result is obtained, if AD can output directly in dxf (or ai), the workflow will be much more streamlined.