I installed a set of R1 Concepts "Premium" solid rotors and ceramic pads on my wife's Intrepid a couple months ago,, I wasn't impressed with the quality of the rotors, but I used em' anyway,
The OE brakes on that POS are horrible in the 1st place and I haven't noticed any abnormal issues with them, No vibration issues or noise.. On the +side,, The pads aren't dusting as bad as the OE pads.
Not sure what the price is for the Mustang rotors you're looking at but the Dodge parts were shipped for $159,, I would spend a few more $$ and get a higher quality set of rotors and pads for installation on a Mustang.
2010 Grabber Blue Mustang GT, Forged 4.6L Roush TVS and other stuff ... The modding shall never end ...
Wife's car ... 2014 Sterling Gray Premium GT 401A, stock for now ..