You make some mistakes with your argument. First, the rotory engine is calculates displacement the same way that the reciprocating engine does, but the reality is that it pushes more air, about three times the amount. So a 1.3-liter rotory is actually closer in displacement to a 3.9 liter reciprocating engine. If you look at racing, the usually use a multiplier to figure out the true displacement of the rotory. (2 to 3 time actual displacement).
As for turbos, that is the same ass adding cubic inches. Bigger engine means more air and fuel. Turbo means more air and fuel. Again in racing, turbos usually get measured as displacement times 2.
Last but not least, the S2000 has no torque, (153 ft/lbs) vs. the camaro (310 ft/lbs). So it needs to rev really high to make its power because HP = (Torque x Rpm)/5250.
The fact that is can rev high, means you can use much shorter gearing to multiply the torque you do have. An advantage the camaro does not have. In the end they will probably shift at the same speed. (Actually I think the camaro can shift at a higher speed because its gearing is so much taller)
All in all, as long as it is fun to drive, who cares?
PS There is only 1 substitute for cubic inches – cubic money