In the Nov issue of PowerLifting USA there is an article by Louie Simmons about his new Zercher harness which makes total sense. Improve anyone's strength and leg mass with this one. Requires more of a proper squating stance, which can relieve much lower back stress. And no serious hand involvement is needed. Might be a great advantage when used for BB'ing. Also could erase any of the tension that the front squat can give some people. Theory around, for many years, is that any squat, with the weight held below the shoulder girdle is better all around. And any exercise with the weight below the hip region is the most superior of all when it comes to raw power and leg development. Something like belt squats and hip lifts come to mind. Even the DL can fall into this class of below the hip region area. Even thinking of the old Jefferson lift in this regard.
That first bar pictured (supplied by Pumpster) is a cam'ed bar. But the handles/grips seem a little short for proper use. In the second picture (supplied by Pumpster) you can see that the plates/weight are lower down a bit from the shoulder girdle, giving a better squating dynamic for most people. The yoke is in place, but the center of the work load/weight has dropped down a bit.The one's I have used have the handles a littler longer and usually wrapped with duct tape. They can really improve anyone's squat, in style and proper form, with a whole new approach to the confidence factor when working under heavy loads.
As the Lovely Princess L was stating, most any form of squating requires a learning period. Just takes reps to get the motor units under proper function. I really can not tell by the picture what that version of her safety bar is. Good Luck.