[The HACK]

The surface of the rotor is what dissipate heat. The 348mm rotor has significantly more surface area to manage the heat dissipation. On that fact along I would choose the kit with the larger rotor, despite the thinner rotor.

And I don't like it when vendors engage in smear campaigns against each other. I used to work in the industry so it pains me to see a quality manufacturer like PFC ragging on another vendor's product to hock their own. There's little reason to do so, PFC hardware is superb and would stand on their own against anyone's product.

For me, the rotors I've been using for the last 8 years from RacingBrake has shown that they're high quality products. Yes, I chose RB calipers because I already had RB rotors on the car. But I also chose RB calipers BECAUSE I had RB rotors for so long and had been impresses with the performance and the life and the quality and know I would get a high quality and well engineered product.

In all honesty, you will get a kit that's far more engineered than your current need with either the RB kit or PFC kit. If both kits come with the same size rotor, same caliper construct, and same price? I'd buy the PFC kit because of their reputation. But if the RB kit has larger rotors, or is cheaper? I'd take the RB kit. If I was racing? I'd take whichever vendor sponsors me. That's how confident I am in either company.