I don't see how that could be true. I can see however, the Cal Tracks and Slide a Links maybe working a little "better" with "their" type spring. But even the split monoleaf works with the same principle as the SS spring. The monoleaf just allows the traction device to "work" the suspension more.
Hell, use slant 6 springs if that's what works for you. People have forgotten American ingenuity had made anything work anywhere.