I looked at the Arkel bag and as soon as I picked it up I knew is wasn't for me; it was just so heavy and over engineered like their classic panniers (however their new drylite panniers look very interesting). After using a couple of boutique cotton duck handlebar bags which were a pain to mount, I ended up with an Ortlieb Classic. It's a nice size, waterproof and the KickFix mount is quick to get on and off. The way it attaches to the bars with two cables is a bit strange so I bought the Rixen and Kaul handlebar clamp mounting system which only uses a single cable to stop the mount from sagging.

Amazon.com : KLICKfix Rixen & Kaul Handlebar Adapter (multi clamps) Ø22-26 mm & Ø31.8mm : Biking Quick Releases : Sports & Outdoors.

Closing the lid of the Ortlieb takes a bit of finesse and clipping the shoulder strap on is annoying, but I can live with those as the bag carries stuff really well on and off the bike and I like it's single large rigid compartment. I didn't buy the map case. I just clip my maps onto the bottom of the lid with a couple of binder clips and it puts it at a nice angle. I put the map in a zip lock bag if it rains. I also carry all my food in the handlebar bag in a large zip lock bag so that I can easily put it in a bear locker or hang it from a tree.