Seagull black bag is a "superior real" messenger bag from what I've read about it. But it does seem to be lacking in pockets from the pics i've seen (2 pockets plus the large cargo space?).
I own a Bailey Works Super Pro myself. It's got the large cargo space, two front pockets (one with pen holders), outer side "bottle" sized pocket. Two inner corner pockets, an inner center pocket and one zipper pocket.
I love my bag. I use it most of the time even when i'm not on my bike. Photography is one of my hobbies and my lenses fit in those corner pockets just right, so I use it for that too since it's much easier to swing around than a photo backpack. The huge reflective strip on the back helps me feel a little more safe in traffic at night too.