Should I buy the Sigma SD15 DSLR Camera or go for the Nikon D300s instead?

I currently don't have any DSLR camera, but I intend to buy a new one pretty soon. I was looking towards buying the new Sigma SD15, the replacement for the older Sigma DS14 DSLR camera with the Foveon X3 sensor. The problem is that I can't find reviews or relevant posts with a in-depth comparison of image quality between the Sigma SD15 and SD14. I have seen some sample images taken with the Sigma