Alrightythen!
The 365 got here and my search is over. All the room I need and then some, and it isn't much bigger than the Producer briefcase style. By way of comparison, the 365 is not as wide as the Producer, by about the thickness of one of the Producer end pockets. It is taller, as you'd expect, by about a third. Again, for comparison, the Producer is wider than the 365 is tall. Size in this case is no issue. Think more square on the 365, more rectangle on the Producer. Either are easy to carry by the sturdy, comfortable handle.
Fit: Here are a couple of photos of things I quickly stuffed inside:
Photo 1: Everything in and closed up. No bulges or oddities.
Photo 2: The end of the AX8 and a large computer (more on that in a sec). Also note the upper front pocket has a cable storage strap that holds lots of cable, and the lower pocket...
Photo 3: ... that has two wireless transmitters and some cables, where another pocket inside has room for more. I put the full size 8.5x11 manual in there to show how wide it is. There's lots of room left where the transmitters are.
Photo 4: That is the AX8 and a MSI GT70 Dominator 17" laptop. There is actually room to put a Mission expression pedal beside the AX8 if I were pressed for space. I used the MSI as an example because it is twice the thickness of a Macbook, so you could see the room. There are actually two pockets on the laptop side, so you could carry a Macbook and an iPad if you wanted, or two MBPs, with plenty of room.
I didn't take pictures of it, but my Shure GTXD wireless power supply and receiver are in one side pocket, and my Mission EP-1 in the other (lots of room left above it for other do-dads).
The case has all the normal Mono appointments, and isn't cumbersome at all to carry in briefcase fashion. Of course, it also works as a backpack for longer hauls or when you don't have a spare hand. And the backpack mode has pads to keep your back cushioned and breathing, just like a good hiking pack would. Loaded up it is completely manageable, and I really like that I have room to put the few more things that inevitably pop up.
I decided to keep the Producer bag too, I am going to use it for my computer gear that travels with my StudioLive boards to keep it all safe and clean. Been a good December around the old music room!