I'm using OneCNC, a CAM software that includes a CAD package as well as solid modeling capabilities. You only need CAM software if you are taking 2D drawings or 3D models or surfaces and creating CNC tool paths from them. My package will import and export STEP, IGES, DXF, PDF, and JPG. My experience has been if you handle STEP and IGES you can deal with 99% of the folks out there. I've been told that STEP and IGES are the two internationally recognized formats.
Not to make anyone mad but it looks to me like most of the guys on this forum are into ARF's and flying rather them scratch building. You might have better luck generating interest in your design at the main RC Groups web site.
Vern