I think we talked about two-piece floating rotors awhile ago in this thread. I am a fan. I've had cracking issues with stock type rotors on a '97 Mustang Cobra and '00 911 during track days. With my '14 Mustang GT I didn't even bother running the stock brakes on track and went straight to the Mustang FR500 Brembos (Grand Am race car brakes) with two-piece floating rotors and a cooling hose and duct kit. Never had a problem with that car's brakes.
I am going to try running the stock rotors and calipers on my GTI with stainless hoses, RBF600 fluid and Hawk track pads (stock power, 245mm track tires and Bilstein shocks/struts with H&R springs). Any sign of brake issues and I am going straight to the Stoptech kit with 2-piece floating rotors. I don't like to fuck around with sub-par brakes on a track like Road America where there are some heavy braking zones from high speed and brake failure could get very ugly.