I picked up my mark iv yesterday. Was a hard choice as there have been a wide variety of opinions on the camera and if it is worth it or not. I also upgraded my 70-200 2.8 from version 1 to 2. After 20 shots today of the kids, all I can say is I am glad I upgraded. I do think the sharpness, noise, resolution etc is noticeably better than what i had before - too my eyes anyway. Have ordered some faster compact flash cards so I can record 4k... now that will be fun!