I am using a Leaf Aptus II 5 22 mp digital back on a Hasselblac 501 CM. it takes great pictures.
when I use a shutter speed of 1/4 sec or less the picture is invariably blurred despite holding the shutter open long enough for the lens shutter to close.
when using a cable release the back mostly fails to get the image, not so when pressing the camera shutter
also need a firmware update