I'm considering whether to make another Bihn purchase. If I do, the choice is between the ID medium messenger bag or the Zephyr briefcase. I do not have the need for a more professional style briefcase, like the Tumi I currently use. I like the Tumi but it goes more with someone wearing a suit and I rarely where a suit. I also do not go to court all that often these days since I have slaves, I mean associates that cover most of my appearances. I prefer to have something more functional and casual and, quite frankly, this is a good excuse to buy a cool new bag.
The Zephyr is the briefcase version of the ID with a bit more space. The one thing I do not like with many messenger bags is the there is no handle to carry the bag like a briefcase. The ID has a handle which is a plus. They both are big enough to carry an ipad and/or a MBA in 11' or 13". I don't think I would use a Brain Cell. While they provide great protection, they also take up a lot of space. The bag itself with an iPad cover and the MBA with a sleeve will be more than enough for protection in either bag. I am leaning ID since it gives me the across shoulder carry of a messenger bag and a handle for briefcase style carry. I guess I should order one as it can always be returned.