When I am merging two areas, and any of them have arc points, I find that two things happen.
1. The arc is turned into segments, and a bunch of points are created. If that arc needs to be cleaned up, now I need to go delete all the points, and convert one to an arc.
2. With large areas, the radii disappear.
Hey Justin - I replied to your other post about the slice area with arc points. Similar situation here, where we converted the arc points into normal points due to the complexity of merging/slicing with arc points. We'll also look into this as well.