Weird. I don't see the conversion to spline after breaking the link of the projection.
Anyway, talking about the bigger scheme of things, our developers are looking into this and you can refer to this defect number to obtain further status on this issue:
Defect 1464270 The hole in a cylinder shown as a spline and not as a circle after dwgout
Bob, thank you again.
I've attached another version of the resulted Autocad DWG, showing the spline which I've tortured a little to indicate it.
Also, what I've discovered in the process is that only the visible circle turns into a spline.
I've changet the through hole into a blind one and created a front an back view of it.
In the front view the hole became 2 separate splines on the visible layer, while in the back view it remained one true circle on the hidden layer.
I think I now see what is going on. Looks like 2012 and 2013 react differently.
In 2012, breaking the projected "circle" results in a spline
In 2013, I get a true circle after breaking the projection.