Hellwig Hollow sway bars

I am also interested in Hellwig and hotchkiss and wonder if they are worth the money. What advantages is there to a hollow bar with the same outer diameter? Is it stiffer material?
Were you guys running sway bars prior to installing these?
If so what were they and was the hardware the same? Like end links, polyurethane vs stock rubber?

Going from no rear bar to adding a rear bar will make a difference regardless of brand. I experienced that on an ebody by just adding a factory rear bar.