My H-A-D 5'er has been around the world with me and is indispensable. A buddy of mine calls it my "man clutch" (like a woman's clutch purse) because I rarely show up at his place without it in my hand. I've often thought of going with the 10 stick box, but not sure I'd reach out to grab something of that size on the go as easy and quickly as I would the regular 5 stick box. It would definitely come in handy for longer trips or when I wanted to bring enough to share, that's for sure.
*EDIT* One thing I wish these H-A-D's had, is a small "compartment" or cutout in the foam just big enough for a cutter and lighter. If I ever get a 10 (or larger) stick box, I may do that with one of the lower levels. In order to carry my cutter and lighter inside right now, I have to wrap them in a paper towel so that they don't bounce around and damage the cigars. For various reasons, I don't carry much in my pockets.