I've been thinking about replacing my 9 year old 50d for a couple of years now, but my Scrooge sense always kicked in when I totaled up the price for a significant upgrade. (The guys here helped me pick the lens compliment for the 50d, by the way). I got more of a push last year when the camera club did some night sky shots and I discovered the 50d had some streaky noise at high ISO that the black-field noise subtraction did not fix. But I still shied away from the prices. Well, I kept hemming and hawing and looking at holiday prices until I mentioned this to a friend who convinced me that I couldn't take pictures with my bankbook no matter how fat it was, so on Dec 31, I put in an order for a 5D Mk IV with a 24-105 F/4L lens and an additional chunk of cash for a 100-400 F/4.5-5.6L telephoto. None of the lenses from the old setup fit except a prime 28mm F/1.8, which I bought as a 45mm equivalent on the 50d and will now be my preferred lens for night sky, I think. Everything arrived Wednesday except the spare battery, and I'm getting acquainted with it all and the 610 page (!) instruction manual. Fortunately, many of the controls are similar to the old camera, and I know enough already to use full automatic, program exposure mode, and full manual mode - it's just all the possible intermediate automatic function modifications that will take some time to learn, like which auto focus mode is best for a certain situation. The 50d was simply autofocus on or off, plus selection of the focus point, and the 5D adds various subject-tracking modes for the auto focus. So now I have a full frame camera and lenses that cover a good range (although slightly smaller on each end than the old setup) but have to find a softer shoulder strap because this beast is definitely heavier with the mid zoom and way heavier with the tele. Also have to get used to always using an external speedlight, as this one has no pop-up. I thought about going to Sony, as everyone I've met who has one has been crazy about them, but in the end I decided to follow inertia into familiar territory, and the bulk/weight is the price I'm paying for the upgrade in addition to the $$. Anbody out there with a 5D who wants to share some tips, I'm listening!