I ran the XHD springs with Cal Tracs....... No problems.
I wouldn't try and use them with SS springs though.

Keep in mind....... The bars were available for quite a while before the split mono-leafs were.

My Cal Trac/XHD combo replaced some well used SS springs, and the Cal Tracs were much more consistent, although best-to-best, they were no better.

I found the Cal Tracs made the rear of the car quite stiff for road use.