I haven't used it but I was under the impression - from a demo I saw - that its purpose is to create a smooth surface for the new stitch regulator to travel over.
I'd read that people have had problems with quilts dragging on the squared off front edge and I'd hoped that this would solve that problem but I don't think it's any larger than the table surface.
Could be wrong about this. You might want to call the company.
I don't have an HQ SS but am looking.