One thing to keep in mind is the people shooting medium format have in general been using that format for many years. The type of photographer is different. the 35mm format has never really inspired the slow methodical process of photography.
35mm flexes towards the more action and telephoto side for pro photographers. Sure you can use it for landscapes and portraits, but lets be honest the design of 35mm dslrs is more grab it from the bag and get the picture before something changes. Some people will argue that the weight differences make it more applicable for travel. But they aren't looking at the whole picture as the differences between the D800 full kit of lenses filter, tripod, batteries, charger, laptop, camera bag, etc. aren't that different from the same thing in medium format. There are easier weight savings than the small contribution from the camera. I carried a Mamiya 6 for many years and it was just spectacular light in comparison. But in the end the complete kit was only about 4% lighter... Whether or not I decide to bring a couple bottles of beer took up that difference.
Medium format hits that medium between the 35mm style of photography and the extremely methodical patience oriented large format photography.
The style of photographer dictates camera selection more than numbers. I don't shoot action, I like cameras that are incredibly user friendly allowing me to focus on the picture and not the camera computer system. I prefer to keep things slow: getting my grad NDs aligned perfect, making sure my tripod is firmly anchored and camera leveled, using my handheld light meter to check the camera's meter, waiting for the clouds to come into position, etc. The bright viewfinders of medium format seem to inspire me more than 35mm. The feel that I have to be on the tripod most of the time makes me focus on choosing the perfect foreground to set up at and then focus on figuring out what I can make of the scene. With 35mm dslrs I just can't focus on the image as much. My photography level saw a drop when I started using Pentax dslrs to supplement my 645N (Film, processing, and drum scans were getting expensive).
I presume there are many more photographers out there with a similar perspective. Many of the people using the 645D are likely using it because of the format not the numbers or price. Because in reality the price isn't that different when you look at everything you have invested: lenses, tripods, special purpose tripod feet, leveling bases, ball heads, gimbal heads, lens plates, camera plates, macro focusing rails, extension tubes, grad NDs, polarizers, UV filters, camera bags, computer software, higher performance computer, camera memory, studio lights, remote batteries for studio strobes, remote switches, replacement camera batteries, solar power, travel expenses, "what ever else your kit includes"...
Leica users are the same way. They pay well over what a similarly spec'd Nikon or Canon costs. They like them because how the camera inspires their style not because on numbers. The only problem with them is they are arrogant...
Last edited by atlnq9; 03-24-2012 at 10:03 AM.