I sure would like to know if and how much noise and throttling actually occurs. HP has said their fan is quiet.
The HP is also larger and heavier than the MacBook. I haven't seen one live, but just about all PC manufacturers say their fans are quiet. Even Apple has done so before. However, nothing is as quiet as fanless. All processors throttle. Even the 15W chips in a larger, more traditional form factor. For sustained operations CPU can make a difference, but in this class, there is little real-world difference. The Core M is a good chip for consumer notebooks, and I think more OEMs should be using it. That way they could focus their design efforts on other aspects besides trying to shoehorn a higher wattage chip into an ultrathin form factor.