I've been having similar issues with Slic3r, it seems to be crashing when I try to process the parts. Skeinforge managed to slice it and so far I've printed the upper and lower ring. The lower ring came out pretty good, but the upper ring didn't come out nearly as well as yours in the picture. Ive got a lot of gaps between the oval holes lining the outside of the upper ring and the perimeter. Not enough fill maybe? What were your settings when you sliced it? What slicing software did you use?