The Saddleback Thin briefcase is actually very close to the dark brown briefcase at the bottom of your post (3rd of 3 pictures) and is available in two sizes.
Had this bag custom made to look like Filson's satchel / Swaine-Adenay Brigg. US tanned bridle leather from Wickett&Craig I think. Iphone pictures only for now, sorry! There are three compartment inside the bag, and one backpocket. Only one compartment is shown.
More pictures : http://imgur.com/a/J3ahG#0