I have a small and a digital. The small would hold your Leica and Fuji but you would probably have to put some lenses in the front pockets. I can put my M240 and A7RII with mounted lenses in the small but there isn't really room for additional lenses inside. It really isn't much different inside compared to the F5XB. The front pockets are larger in the Billingham though. I bought it used and probably should have gone for the regular sized Hadley.
Awesome bags BTW. I have a F5XA and a B. Getting rid of the zipper/velcro is nice.
For a single camera the Hadley digital is amazing. A little bigger than the 5FXA but the dimensions are much more usable. I can fit the M240 (or A7RII) with a 50mm mounted, Konica 90mm, Voigtlander 15mm III, Voigtlander 25mm and a UC Hexanon along with optical finders for the 15 and 25mm all insider the bag comfortably.