dave, 0.830 COR is 0.830 COR is 0.830 COR. Given the same swing speed and same launch angle every head today will be the same distance. If a head was longer than the others, it would have to be USGA non conforming.

There is no one longest driver.

All a robot test would tell you is what head hits it farthest for how that particular robot was swinging -- the swing speed and angle of attack and don't forget how the robot loaded that particular shaft. Unless you swing it exactly like that robot, the information gathered from a robot test doesn't really mean much.

What you need to find is the head that launches best for you and your favorite shaft. The head that gives you the best launch angle based on your average angle of attack, based on your average swing speed, based on how you usually load the shaft. Bang makes a lot of different heads, one they each perform a little differently. But, there is no one "longest head" anymore -- that is regulated by the USGA. You are asking a question that is essentially impossible to answer. Go to a well-stocked fitter and find the combination that works best for you and your personal, individual swing.