In this test, the image was taken with just the SCT adapter, yielding the same 4.25" CCD distance from back of OTA. But, the focal reducer was mounted with just the SBIG nosepiece, which reduced the recommended 79mm spacing to 47mm and a reduction factor of approx. 0.61x.

Not too bad. In the next frame, the same image was resized 50% to simulate binning 2x, which is my customary method and yields an image scale of 0.95 arc-seconds per pixel.