A nice read!

What is the purpose of the LDO? Does it even reduce power draw? The voltage drop is a dead loss in an LDO, in the sense that the reduced power I * (Vin - Vout) is just dissipated in the regulator, but is there a secondary effect that saves power? Or is it just to better control the voltage for another purpose (one could be to move power dissipation away from the core)?

One advantage of the FIVR is that the power from the motherboard VRMs to the processor is about twice as high as in a conventional system.

I believe "power" should be "voltage" in that sentence.