Was thinking about this today when I was looking at the different bags that I have. Seeing that Tom Bihn bags are the height of functionality, why not make a cache with rails that has the horizontal orientation on one side and the vertical on the other? This would allow someone, like myself to use the same cache for my MBP 13 in my Synapse in vertical mode or horizontal in my Pilot. I understand the premise that the laptop opening should correspond to the orientation of the bag, but I doubt that the laptop would just fall out if the orientation was not only vertical or horizontal respectively. I would assume that a vertical cache orientation would be most functional as it would have the smallest opening if flipped to a horizontal orientation. There are so many people that have multiple bags that I think this would be a no-brainer for many people. A sacrifice of ease of removal while still in the bag will obviously have to be made, but that is a small price to pay for not having to purchase multiple caches for the same laptop.
If this isn't something that TB is interested at making, Can I purchase some excess rail material to have a seamstress make this happen?