Magus,
I have the Leica one (small) and it will fit:
Body plus std/short lens
Two lenses on either side
additional lens in centre recess underneath the nose down body with lens attached.
So, thats one body and 4 lenses. You can then fit a spare body inside the front zip compartment quite easily tho it is not as well protected, but IMO fine. so, at a push: 2 bodies and 4 lenses (mine are 28, 35, 50zm + 90 elmarit M). Tight but fine!
I am developing a carriage system based more upon pouches and pockets so that kit vanishes with no bag in view, however. I far prefer this as both bands are also free. Not so easy in hot weather though of course!
Rgds