From what I've been told by BJ, Dana & the likes, the only advantage of the rotor is that it lasts longer & resists warping. It provides no additional stopping power. (That's the only way it got approved for use in PTwins)
You can find a SS brake line on the net for 50 bucks from
HEL Performance Stainless Steel High Performance Motorcycle Brake Lines Brakelines Brakehoses Brake Hoses
I was gonna buy one of those but haven't gotten around to it.
EBC Pro-Lite Contour Brake Rotors - Kawasaki EX500 - KneeDraggers.com EBC Brake Pads - Kawasaki EX500 Ninja500R - Read Reviews and Buy at KneeDraggers.com