I have a maxpedition messenger bag that seems to function similarly. Although I don't use it for concealed carry, just as a range bag. I did go ahead and buy the holster that velcros in for desert trips to easily store one pistol while using the other or fiddling with more ammo etc. It has a slot on the outside that could probably be used for standard belt holsters too while keeping the pistol mostly concealed. I guess I got a mursegun bag without knowing it!
The only issue I could see with my bag for actual concealed carry is that its entirely soft, so the bag folds around my hip when worn, I tried various positions and without sticking something hard in keep the bag straight I don't think one could easily draw. there was too much interference for a clean draw.
That is a pretty sweet briefcase and with the big loop field on the inside you could also look at maxpedition stuff if you want to add some pouches/pockets or mag holders.