I've been using a Canon 6D for several years and am pretty happy with it. But I can't help wondering how much technology may have improved in the past two-three years. I do a lot of hand-held, low-light photography, so good auto-focus in low light and most especially good quality at high ISO are the most important things to me. (I shoot often at ISO 3,200 and get good results with the application of a little NR in post-processing. And not bad even at 6,400) Is there any way to compare current Canon DSLR's for IQ at high-ISO? I know reviews usually look at that, but not in a systematic way that would allow me to compare cameras. I would upgrade from my 6D if I knew I would get a noticeable improvement in low-light.