Single point of attachment, uneven balance, hard to adjust properly
Yes, I know the A5 only has one point of attachment for a sling, but unless you have a remote, the balance is all screwed up and the marker is bouncing a little above your knees, hitting you if you try to run. But if you have to climb - comes in handy. Also has a very usefull quick release if you need to get more freedom of movement with the marker
Well, it is better then carrying it in your hands, but you cant sling it.