I'm requesting real attributes, not variations on the same theme. Greater format flexibility equates to greater pixel count. We know that larger formats tend to have greater pixel count and therefore tend to exhibit greater resolution on large prints.
The 18mp 7D has greater format flexibility than the 12.7mp 5D because it has greater pixel count.
So we're left with prestige. That's what it's all about. I'd agree with that.
Although it kind of feels like I'm being baited, I think it's a fair question, and maybe is a good one to put into the context of actual shooting. Here's a very brief set of examples of scenarios that I'd use particular cameras for- it's about as specific as I can get, and it's very, very subjective, but it's based on the specific characteristics of the various cameras.
A couple of caveats. First, the premise is that the cost of the equipment is immaterial. Before you howl, this is more of a business plan issue than an equipment issue, and it's a result of the cost of digital cameras. As of around the mid-90s I do not own the equipment I shoot with, period. I rent everything. The rental cost is billed to the client, and is a line item. Thus, I don't carry the overhead of the gear, and I use gear that's appropriate for the assignment. (I do the same with the car- every location job has a car rental- it's the best way to expense travel, IMO, and to date, I've not had a single client even ask about it. Again- this is a different subject, but the core issue is it frees me to use the right tool for the job.)
Second, not for a long time have I identified any part of my work with the camera I shoot with. I am not a Nikon, Canon, Hasselblad or Sinar "shooter". I know many cameras pretty well, and thus I'm pretty comfortable shooting with almost anything in a work environment. That said, I read the manual.
Let's go through some stuff that's on my table right now...
I have a 2-day shoot for a furniture designer. (REALLY nice stuff.) I want to shoot with the Hasselblad HD40D, simply because it's in the studio, on a tripod, we shoot a fair amount but narrow it down to a few takes and delete the rest. We then have to do a fair amount of post to straighten perspective and fix up the obvious prototype issues. We deliver images typically sized to a double page spread, but mostly they're used for a web site. This is a case of trying to cover any possible usage, so if we were to shoot it with anything less than a Canon 5DM2 for example (which we use as B/U) it may create problems down the road. Keep in mind his investment for these shoots is huge- he only wants to shoot this stuff once.
We have had problems with aliasing on these products- but the bit depth and resolution of the files, plus the small number of finals makes it a good tradeoff.
I have a model shoot, for the girl's headshots and card. I probably will shoot that with a full-frame camera, just to allow for a little more than I really need. I really like shooting that work with an APS sensor, just because of the crop factor- I can use shorter, faster lenses for the same "tele" effect that I like on models. (My fave all-time lens/camera for that stuff is my old Nikon F2AS and the 105 f2.8 Nikkor...) I wouldn't use MFDB for that for a few reasons- first, the files are just too big. Second, I like to be able to shoot faster if I need to. Third, the camera itself is just massive, and I'm getting old.
That said, I recently had a model shoot that may
be, at some future point, used for big repro, double page spreads or even signage. Not as a CYA, but as a "cover your future use revenue", I shot that with MFDB. The client got the files prepped for exactly what they wanted, but if they come back to me for something they didn't anticipate but I did, then I'm covered (and they WILL be billed...).
I shoot stuff for website sales constantly. I use the Nikon D5000, the only camera I actually own. It's cheap, it paid for itself in one job. It's a permanent setup, so its truly drop-and-pop, and it tethers to my laptop. That stuff gets ripped down to 600px immediately.
I could go on, but maybe this helps. In a sense I get your point- most of this just gets back to the essential facets of MFDB, but the devil is in the details- how those basic characteristics of the tools change how you use it, and what it's good at, is where it gets interesting.