A 22 Mp back from 5 years ago still blows away any DSLR on the market.
I think it's humorous reading about these differences and comparisons between cameras. Of course I don't shoot huge landscapes for a living, but I do wonder just how many people in the world are in fact making a good living at it. I can think of not one of my hundreds of favorite images over the years which would have improved from more "micro-detail." I am talking about my own work, prints I see in galleries, magazines, museums, etc., etc.
I believe there are micro-differences, but I believe that these have little to do with the goodness of an image. I mean seriously, go over to your bookshelf, flip through the pages of some of your coffee table tomes, and tell me what you see. How many would have much greater impact with 20% more detail?
And as has been said many times, do what your business requires. Have your clients ever asked for more micro-detail? Do they even see it? Do they care? I use a variely of camera formats from 4x5 to polaroid to 5D2s. Just the 5D Mark I cameras have earned me 6 figures per year for the past several years, without any complaints from clients. One client had their best sales day ever during the economic meltdown just this past November - with sales exceeding $1.1 million on the Monday following Thanksgiving. The ads were all shot with the lowly 5D, with no complaints about micro detail or anything else. (and no moire either ;-))
I know that in terms of investing in my business, spending on plane tickets makes a lot more sense and will better my portfoilios to a MUCH greater degree than spending huge amounts on cameras.
I think about it this way: given my portfolios as they are today - if I were to have shot everything inside with a 40 or 50mp back, they would essentially look the same. . Now if I had spent that same $30K or so on traveling, hiring talented stylists, locations, models, there would be a huge difference in my portfolios.$30K sends me on a lot of trips, and could potentially transform my portfolios. In my experience, what you put in front of your camera is 95% of the battle. The camera itself: 5%.