And remember, we are comparing the CAS approach to the AT approach in other respects besides just the research investment. And the AT approach also has other negatives, such as MUCH higher officer and MP cost, both of which are weaknesses for Japan. A single CAS wing requires no officers at all, versus 100 for an AT brigade. And while the MP costs are a wash unit for unit, you need far fewer CAS units than you would need of AT brigades for the same job, so again the CAS approach is a huge savings. Considering Japan's chronic shortages of both MP and officers, this is another major nod toward the CAS as the more efficient approach.
But the bottom line remains one of personal style. If the AT method seems more fun, jump on it with both feet and to hell with the nitpicky math stuff!