Benefits? Absolutely none.
Funny thing about leaning the shocks inward is that while it allows a longer shock you no longer need one. More angle on the shock decreases the shock travel for a given wheel travel, so you can get more travel with a shorter shock.......kind of defeats the purpose of using a shock hoop to allow use of a longer shock.
Any benefits to having the shocks leaning more? No, none. By reducing the shock travel relative to suspension travel you are loosing dampening. The straighter up and down the shock can be mounted the better control and dampening the shock will provide. This is even more true when controlling sway, where sway control is gained from the shock (especially the top) being mounted as outward as possible. Those setups where the shocks are leaning inward and the tops are fairly close together can provide little stability or sway control, since the roll axis is close to the upper shock mounts, so there is very little shock travel to resist sway.
Mounting the shocks on opposite sides of the axle helps to resist axle wrap, which XJ's have a particularly bad problem with due to the spring over leave spring placement and relatively flat springs. Mounting both shocks on the same side of the axle won't effect anything if the rig is equipped with a good traction bar, but without a traction bar it will lead to more axle wrap.
Not trying to rain on anyone's parade, just answering a good question. Cross may not be offering shock hoops any more because few wanted them. As far as getting good articulation out of the rear of an XJ, it's not hard to do with an 8-10 inch travel shock. Put a small wire tie around the shock shafts and go twist it up to see how much travel you are really using.
