I ended up with the baseline nad I love the bag. I found it really helpful to go to a store and look at the various models. Mine has this compression technology that lets you fill the bag extended and then compress the whole bag. I think these 1 inch differences are usually going to be trivial with respect to how many shirts you can fit in, but maybe you have a unique situation. For me, I someitmes want to bring a tripod - will it fit diagonally? That 1 inch might make the difference. I wanted to be sure I could use it on intra-Europe flights, so I went small. If I bring a tripod, its tiny or I have to check the bag