I was wondering at what level of enlargement you think you can see the advantage of medium format over 35mm? I ask because I set myself this little task and compared 35mm and 6x7 like for like and was rather surprised by the result. To put it into context, I mainly shoot Nikon 35mm, usually prime lenses and usually on a tripod, but when I have the time I like to take out my Mamiya RB67. I shoot Ilford HP5 and FP4, Velvia and Portra on both formats. I process and print my own monochrome, but send out the colour work to a good lab. I tend to enlarge mostly to 10"x8" with occasional images up to 12"x16". I know quality is not the prime consideration sometimes, there are so many other things that make a photo great but I was using this as an exercise to judge when to take a 35mm outfit out with me vs the heavier medium format. Really I was using it as a justification to myself and to my familiy why I was lugging around the RB67.