In reply to jkarran:
Interesting video. The skinny new Dyneema is so compact, it makes it less obvious when something is clipped wrong. But I don't think closed slings are the answer. I have found there is more danger of cross-loading with the closed slings. The geometry of modern crabs tends to make them hang straight if they are free to move, but if the crab gets knocked sideways and is constrained by a tight loop, it cannot right itself. Many times I have seen a crab that has lodged itself sideways in one of these closed slings and the rope running straight across the gate. Also the closed slings tend to be too stiff to twist around freely. Whilst this may make clipping easy, it means that if the rope gets pulled the 'wrong' way, there is an increased danger of the crab unclipping itself, especially with the shorter quickdraws. I have seen this happen.
Open quickdraws are much more versatile when linking runners together and in numerous other situations. When using rubber bands to hold the crab the right way for clipping, adding one or two further up the quickdraw, holds it tightly together to prevent tangling or double-clipping like shown in the video. Unless a climber racks their gear very messily, I feel this is safer overall than the closed slings.