i read the reviews on the R1 concepts site and on other forums and they are pretty mixed. a lot of people said the E-Lines warp in about a year. The premiums are what i'd go with, but there a little out of my budget at the moment...
For those getting the warping on the Eline series, I honestly would have to suspect either abuse or something else in the braking systems causing issues that would cause the calipers not to release the pads causing excessive heat. I have run both the premium rotors (which are amazing) and the eline series on several vehicles without any issues. I use the eline series on regular street vehicles under normal conditions up to and including moderate towing. I use the premium series on 3/4 and 1 ton trucks for heavy hauling, etc.
I have been selling both since 2009 and have yet to have a customer come back to me complaining of any warping, etc. I am not saying it doesn't happen, but I also have to wonder about the vehicles getting the warping or the abusive driving habits of the drivers. While they are quality rotors, you still cannot expect to abuse them with aggressive braking all the time and not expect problems. I WILL say this, my wife is one of those folks that will not attempt to hit the brakes until she is about ten feet from the stop sign/light and I put the Eline series on her Denali in November while only installing them on the rear in Feb and we have about 15K on the fronts and other than a little dirt/ road grime (because I don't get in there and scrub them constantly) they are BARELY showing any wear at all. Much less warping.
I also sold a set to a local farmer that I haul trees for for the front of his 3/4 ton Duramax that is under a load daily, he did not install them on the back of the truck, just regular rotors with the ceramic pads and he has yet to have any issues, and he is not nice to his trucks at all...
Like I said, I am not saying it doesn't happen, I just have to wonder about not only the operating conditions, but the overall condition of the other parts of the braking system, fluid, and the type of pads used.