This has turned into a very interesting and thought provoking discussion. Nice to see so many ideas, suggestions and perspectives shared. Really appreciate some of the comments from Marc, links and thoughts from Rob and Thierry, and others. I keep coming back to my original thoughts about needs and use, versus wants. The IQ and use options from MF are clearly several cuts above anything else most of us work with. It also has its own "addiction" that does pull one in. This is great stuff.
Putting the entry costs aside (yeah, right....like they do not matter too much), there is a very different kind of shooting transformation that folks would also go through on the MF side of the world. Just thinking back about how many snaps folks take and share now with the M8 or other cameras, and reading through some of the discussions about image management, processing, etc., there are very different approaches and learning curves folks should consider. I think Peter was commenting about how much post processing and lighting that goes into a lot of the shots for MF, and I tend to agree. Not saying that one cannot get great stuff right out of the camera to start, as that is always desired to start, but the effort levels between "grip and grin" shooting, tourist snaps, street shooting, etc., and finished images for commercial use from MF systems are not in the same category. I love seeing some of the final images, and that does suck me in more and more toward MF. I also am not afraid to spend the time planning and prepping a shoot, and then processing later. The difference comes into play with the client base one serves, or if not a pro shooter, the desired purpose of one's shooting. Folks doing commercial, fashion, product, high-end portrait, fine art, etc., type shooting seem the natural fit for MF. Folks doing more event, PR, casual portrait, most weddings, and tourist type shooting seem to fit nicely with things like the M8 and most DSLRs. Folks engaged mostly in sports/action, or a wider variety of shooting seem to have a best fit with DSLRs. Not saying one could not cross over into any other area using any format or system, as we know that is possible and is done all the time. My point is more to think about what one really wants their photography to be or accomplish for them.
In my thinking, digital MF is head and shoulders above everything else for IQ, but it also is much more limited for some things. Marc's points about just using it as one would any other system are excellent, and I embrace the concept. There still are situations where MF is still not going to deliver as easily/quickly/cheaply/effectively as some other tools. If those kinds of shooting are a big part of one's work/choice/preferences, then MF may not be the first nor best choice. Having said that, I find myself preferring to think more about using MF and changing what and how I shoot instead. (I shoot a lot of polo that requires 400mm+ fast lenses, and 8+fps speeds to capture those moments. Nothing in the MF world that I have seen will get that kind of coverage for me.....nor could I realistically manage thousands of MF frames per shooting, even if the camera could deliver it.) That being said, it gets me into thinking more about changing the "what I shoot" part, and that is a hugely scary thing at times. That is why this entire discussion around gear and its capabilities is so useful. It is getting me to think differently about image capture and use. It is getting me to think more about the total image quality, more than the unique capture that DSLRs permit for me now. Starting to be one of those "been there, done that" moments before moving on to that next challenge and probably an entirely new set of clients. Yikes!
Bottom line....when I figure out the best way to overcome the MF entry hurdles again, but now on the digital side, I will, and probably never look back, except keeping the M8 and a few select lenses for personal shooting. I will not worry about insanely high ISO needs for high shutter speeds to stop 40mph horses running past me in after-sunset light conditions, and not using any flash.
O.K., who was it that was asking for a "selection matrix" of sorts to really get this stuff figured out? I applaud that creation and tool. Objectivity is important, but wrapped with a bit of passion is good also ;-)
LJ