IMHO the optimum height of the connector is a function of how much power, how much traction, and the wheelbase (longer = more flex).
On paper, 2" wide X 3" tall is much more rigid than 2 X 2 (over 2-1/2 times), the question is "how much is enough"?
I wonder if anyone has done a specific size install (2 X 3 etc.) and tried to jack up the left front, and measured how far off the ground the right front went up vs. another size?
Obviously, at some point the connector's stiffness exceeds that of the remainder of the chassis, and the right front will come up simultaneously.