Thanks everyone for your input.
Jakeman, I figured we were not talking apples to apples comparing Class D to a Class A-A/B and that not all theories apply to all situations.
I'll read some more on this topic as well. I've noticed that most of the well known reputable amp companies out there design their amps with higher capacitance, especially if they are type A or A/B or A-A/B. So what you say makes sense about efficientcy. I'm sure they design the amps that way for a reason and are not just doing it to be snake oil salesman.
Heck, Tom C from Axiom himeself used to design huge monoblocks back in the day, and I highly doubt he would be creating amps with extra capacitance unless it was required.