Thanks Louis! I'll measure it out and see if that will fit my arm. I was originally going for a Storm case because I like the button-style openers, but they don't seem to have one with the right dimensions for the arm - the closest one ends up being so wide it's almost the size of my sled case, and until I get a larger car that's not an option with my existing cases and plans to buy a cart soon.
David, yes I have multiple reasons for keeping it separate. First, I have an Exovest, and since I like to keep it set up for me to wear right out of the case (set for a small frame overall on the vest), the arm in the soft bag mashes the pads too much for my liking if I store the arm inside the vest. Since it's memory foam, I wasn't fond of storing or traveling with it that way. The other reason is I live in a third floor walk-up with a narrow staircase, so I try to keep my cases relatively light for that reason - don't need to be tired before I've even finished loading the car, not to mention coming home after a long day and hauling them back upstairs (while trying not to wake up my two year old neighbor on the other side of the wall)!