If you treat the front as a unit, you can increase traction as the wheels sysle up and down. aA the left wheel drops into a hole, the right one is compressed, the air can move from the right shock to the left one. Decreasing the support from the one on the right, (the tbars will be holding the load by now) and putting it on the left one(the tbars will not be doing much at full droop). This will increase pressure on the drooped tire, without needing a full out sas. It will also give a little better ride on highway.. If you are looking at replacing the tbars, air shocks do not have the loading capasity to support the front end on a downhill by themselves.. (at least not the ones that fit)
I have rancho 9000's, if I had it to do over again, I would have gotten airshocks instead, and mountes an air ride sensor from a big rig to the rear axle, and the rear ride height would be the same no matter what I loaded, or towed.