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For my Micro 4/3 use and gear choice, the 107 and 307 hold similar gear to that of the Hadley Pro. The difference being that the 107 and 307 are stable on the ground; have a superior carry handle; capability to accept tripod straps and/ or rucksack-style straps; and they utilize the Delta pockets. (I like them more than the Avea)
The 07 series implies that you'll set them on the ground to work out of them due to the inner carry handles that reveal themselves once you've opened the kit. That, and the metal feet on the bottom of the bag. You grab the handles and convey the bag to the next spot you're working from. This came in handy for me such as when shooting a WWII reenactment. I didn't know the conditions and brought a bunch of stuff and had no need to keep all of that hanging off my person while shooting. There were tall dry grasses and it was all okay getting in and out; maybe zipping up once in a while.
Hadley pro holds an extraordinary amount of Micro 4/3 but at the expense of accessibility. Stacking gets you there.
Here is an old post I did in another forum, one dedicated to Micro 4/3 gear and the 307. This is more of a continuation from a prior section of the post that is less relevant here in this thread.
Of course, I couldn't help myself but get a Delta Pouch for outside. The phone is available there and there's a spot for my glasses. (I like shooting without wearing glasses and they get bent if I try putting them somewhere in clothing pockets.)
Before I'm done, here's a pic of the Macbook Air inside the closed bag you saw. Guess what? Billingham must be reading forum threads because the bag is no longer stitched in that spot. Bag buyers were cutting interior stitches so that laptops can be slotted within.
And, I found a use for the flap that came with the bag. A nice little table for swapping while the bag is on the ground. Not a necessity, but it's available if I want. The flap when not used like a table top gets slotted into one of two openings on the side where Billingham has maintained stitches to keep the inner container in place.
What about the smaller 107 and 207?
What is the impact of going with the two smaller bags in the series, the 207 and 107? If you are using the same size Superflex inserts as I am using, you wind up losing 2 silos and 4 silos respectively; each bag interior with a little bit of space left over between the last Superflex and the inside wall. The 107 gets you more space due to how it works out. How useful that extra space is in each instance is up to the individual photographer. The image conveys this; two cardboard strips were cut to the interior width dimensions that B&H says that the two smaller bags are.
Here's a recent schematic that helps envision more than the cardboard strips allow for.
What to make of it? It appears it's about whether you want to carry a fully gripped camera with a reduced set of lenses, albeit, readily accessible lenses… lenses that can be setup with hoods extended and perhaps rear caps off, ready to rock. Both smaller bags when empty weigh successively less.
So if you want the fully gripped camera and one of the smaller of the 07 series and that camera is occupying it's spot like in preceding photos, then you wind up with three available chambers for the 107 (body and four lens chambers) and five chambers with the 207 (body and six lens chambers); as compared to my seven chambers with the 307 (Body and eight lens chambers).
Recall that it'd be a nice idea to have an empty slot or two available for swapping; or for dropping something in there in a hurry, such as a lens cap; or to drop-in a hood that you might have removed for some reason. Remember, we don't always have a table nearby and the ground could be hazardous. A bag depth that supports a double row of chambers is kind of like a safety net from lens drops. We also know that the lens chambers can be handy items for other than lenses. Like flash units, small parts, bulb-blower, a can of soda, whatever.
Last, what about a laptop or tablet for the 107 and 207? What is certain is that going smaller than a 307 loses you the Macbook Air slot. Roughly two inches are gone from the interior's width. But what about a tablet computer? The 207 accepts a recent model iPad (the regular size one with Retina, not the new Mini). Just about; at least the one I tested with a full back case and cover. So the 107 is one I don't know about. Maybe an iPad Mini might fit; at this point I don't know. Owners of the Mini might compare specs with the 107's 9.45 inch interior width.
I feel fortunate to be in a position to see this for myself and to share it with the community. I hope this will be helpful to someone contemplating this kind of bag for Micro 4/3 use.