I don't see any major difference with my replaced sensor. As I posted before, there might be some very minor and subtle differences, but this is possibly due to my imagination. You get essentially the same images.
OnSemi pulled the datasheets for the KAF-18500. The BG-55 cover glass has 10% less transmission than the older S8612. The new CCD has a new Color Filter Array- different dye than the original to compensate. I suspect it will be very close, and you would have to use a calibrated light source and histograms to really see a difference.