I have a Bailey Works Super-Pro, my friend has a Seagull. They are both great bags. Seagull has tougher velcro (more like Chrome & Timbuk2), but I've never had any issue at all w/ Bailey Works velcro.

Seagull has the nice option of back padding. Bailey Works has the laptop sleeve, which can be added, and works the same way, + it carries a laptop.

Seagulls are more customizable, if that's something you want. Bailey Works, you just pick a color.

Bailey Works has a split-strap, Seagull does not (I don't think). It's a nice feature, but I never actually use it.

Bailey works has far more compartments. Bucket pocket, two outer bellows pockets, one with a small pocket + pen holders, one exterior side pocket next to the bellows (another can be added for $), inside, two side pockets (Think water bottles, tubes, tools), also inside, an open pocket (separate from the bucket pocket), and a zipper pocket. Seagull has the bucket pocket, two exterior bellows pockets, and a small velcro pocket on the inside. Nothing more.

Both handmade in the US.

Both have stabilizer straps. Bailey Works comes across your rib cage, Seagull comes a little higher, under the armpit.

Both ride well, cinched high & close to your back.

Bailey Works has reflective strips (at no extra cost). They do work well, and one is located on the bottom of the bag, which is the side that faces cars while riding. Seagull has no reflective strips.

One more thing- the only complaint my friend has about Seagull, is that the corner of the flap sticks up when closed, so it obstructs her view when she looks behind her to check for traffic. She remarked to me that she likes how Bailey Works "hugs" the body, meaning, it wraps around the shoulder more, and doesn't obstruct the view. I had never thought about it, but she is right.

That's all I got.