Here's a picture of the slingshot bar depower I use on my SS bar:
http://www.chicagokitesurfing.com/safet ... rmods.html
In terms of spinning, if the shackle is reversed so it is static-attached to the spreader bar and the loop is shackled-in, you can run your leash to the shackle and attach it to the shackle-door ABOVE the joint, so the leash and bar can spin as one device, and if you release the shackle, the leash will still be attached to the shackle, holding the kite.
I'm going to do this to my bar, as well. The other bar looks real nice, though. Just another option for those that have some components and don't want to spend the whole $ on a new bar setup.