I don't think that any of the inexpensive 3D CAM programs can output arcs instead of straight line segments. I talked about this with the MeshCAM developer several years ago. You should be able to fit an arc to the first 3 points, then check the next point, if it lies on the same arc, then continue. Otherwise, start a new arc. I think the issue is that the entire internal structure of the program needed to be changed to accommodate this.

I've read somewhere about someone writing a utility to read the g-code and convert the line segments to arcs, but I don't recall ever seeing it anywhere. Since Mach3 doesn't have any issues with the straight segments, there was no reason to pursue it.