Way to really pull out the calculator and get to work!
However, while power and work measurements are great starting points for the analysis of exercise, they have certain limitations.
For instance, by the same logic on the basis of which you have insisted that tabata air squats are 'superior' to weighted front squats, I could argue that running 1600 meters at a good clip is superior to doing 'Grace'. For me, running 1600 meters requires moving 175 pounds a distance of (can you guess? :lame:) 1600 meters. Grace requires moving a barbell forty pounds lighter than a meager 200-250 feet or so over the course of the workout. Even if you could somehow figure out how much I move my bodyweight during Grace and factor that in, the work performed during the mile would still dwarf that of Grace. And since it takes me about 5 minutes to do either Grace or the mile, the power requireement of the mile dwarfs that of grace as well.
But we both know that running a steady-state mile is certainly not superior to doing Grace; it is simply a different kind of stimulus, a more monostructural stimulus and (with respect to fitness in general) perhaps a less useful stimulus.
The problem with using work and power output as the basis for an analysis of usefulness of an exercise for fitness becomes dramatically apparent when one tries to compare exercises that chiefly train the CNS to exercises that chiefly train strength-endurance and wind. Marathoners do a lot more 'work' than oly lifters and sprinters.