I am 100% certain that MF shooters are not a target audience for any of the bag makers. Case in point, how many of us are 'bag of the month' club members? I've got 67, not including the bags that can hang off my ThinkTank belt. I just got back from 4 days with the H4d, a 35-90, the 80+1.7x and a few other things along side my 15" MBP. My back hurts, my shoulders hurt, and that's not the worst I've done to them (did this with the 150+210 in addition before). I'm looking at getting a used 11" MBAir just to cut out as much tech excess as possible, since I need a full machine for the day job.
The body size and lens sizes are beyond what 35mm folks deal with. I wish ThinkTank did a LensChanger sling that accommodated the 95mm filter stuff that Hass uses everywhere. I fully believe that MF folks are more than willing to pay more for a bag designed to our common sized gear. Otherwise we'll all be in Pelican cases with wheels (I'm too young to admit defeat). I kinda like the Chrome Niko bags I have, the Messenger is perfect for my H with the 80mm and I have the 1.7x sitting upright next to it, while the Pack can take a load, but damn it, I shouldn't be carrying around 50lbs of gear - I can fit that much into/on it.