Looking at the YJ one, I can't tell if it's a bolt on or a weld in cage. It also doesn't (anywhere I can find) what tubing it's made of (the TJ kit is .120 DOM, but...) and I can't see how the stanchions tie it. Without a tub tie in at the floor board I'm not sure how much extra protection the cage would provide.
I put this one in last spring and has some better details of what I'm describing (not the same thing for the same price and it's a TJ sport cage, but...)
TJ Roll Cage, Roll bar