Do a search for revolver shackles and you will get a ton of stories on them.
I found that with them on the front of the Jeep and climbing, when you crested a hill or ledge with a sharp lip-they would drop down (unload). This really changed the weight transfer, traction, and overall feel of control.
On the rear, going down a ledge or drop was worse as when they unloaded, it threw the rear up even farther; contributing to the out of control feeling.
They also gave me alot more flex, but it didn't feel like it was controlled or beneficial to traction. Just felt tippy to me. At any speed above slow on desert roads the Jeep leaned alot more than I liked, and if it leaned enough, the shackles could unload causing trouble. Just my .02 worth.
Please read up on the shackles, decide for yourself if they may be worthwhile. If you try them, just be carefull until you know how they will react.