Below are charts out of a very recently published study from the Sloan Automotive Laboratory at MIT. The study examines the cooling effects of direct injection under high load operation. The study took a Pontiac Solstice engine (GM LNF, direct injected 2.0 liter turbo) and equipped it with port injectors. Note that the Solstice uses a multi-hole type injector, not a fan-type like the Toyota D-4S system.
The researchers figured out an average combustion chamber pressure trace at a borderline knocking condition using direct injection only and then port injection only. They kept the rpm, spark timing, and intake air temperature constant.
Then they heated up the intake air and tried to figure out how much hotter the intake air has to be for direct injection to have the same borderline knock combustion chamber pressure trace as port injection. The method was used to calculate "effective charge cooling" of direct injection, especially with ethanol fuels.
The charts display the palpable benefits of direct injection in mitigating knock. You don't have nearly as much of the latent heat of vaporization being wasted.