James,
This matches our test data pretty closely. And yes, the 393 motor was designed to be a superior motor. The original motor was good for the beginning of VEX, but as the VEX Robotics Competition has evolved and teams were making more advanced designs we needed to make a more advanced motor that pushed the electrical power limits of the Cortex.
During the development of the new motors (393 and 269) there was a lot of debate within IFI about whether we needed to have both the 393 and the 269 or just move to the 393. The discussion was entirely focused on how our customers would react. As I had just started at IFI, it was my first real look into just how much this company cares about the customers. The final argument that kept the 269 was that we needed a motor that could fit in where the 3 wire motor fit and had the exact same motor performance as the 3-Wire. As you know, the 269 is slightly smaller than the 3-wire motor and the 393 is significantly larger.
Now that we have significant technical and competition data, it is clear the teams prefer the 393 motor (duh). The 393 motor is a more robust motor and can withstand more abuse than the 269 since it has a significantly higher stall torque.
Now on to the numbers (269 and 393). How did we come up with those? Those are actually the power numbers in Watts (well the power is actually 2.69 and 3.93) from our initial testing. Now if you do the actual math on the published numbers you will get 3.99 Watts for the 393 and 2.54 Watts for the 269, but the names were determined during our initial prototype testing. Anyway, just a bit of a history lesson.
Paul