Testing casualty claims for Operation Downfall

How reliable is the Operation Downfall study Hell to Pay?

It is a worthwhile study, but its casualty estimates may be too high because they give too little weight to Allied firepower. An invasion would still have caused far heavier losses on both sides.

Hell to Pay receives a qualified recommendation as a study of the planned invasion of Japan. Its loss estimates are challenged for underestimating the firepower available to the Allies. That criticism does not make the invasion a low-cost alternative: losses on both sides are still expected to have been far heavier than those suffered in the actual conclusion of the war. No replacement casualty total is offered.