I haven't seen any testing to substantiate that. In fact to the contrary, I've seen multiple tests with the reference blower at 100% to negate temperature being an issue with rock-solid 2Ghz performance. It is very loud at that level though.the better power delivery in AIB cards results in a more stable Boost clock, if not a better overclock. A sustainable Boost is reason enough to skip the reference card, in my opinion.
Until we start seeing people sustaining >2.1Ghz, there is no real reason to get anything other than the reference PCB with a nice AIB cooler to keep the noise down. Again, I pre-purchased an EVGA FTW myself, so I hope that's wrong-- there just isn't enough data yet.