We found that, because a back catapult requires a greater range of motion than a front one, the pistons can’t have the same amount of leverage as they can on a front catapult. A 4 piston back catapult can have half as much leverage with the same amount of force, which I think is why teams like 44, with 4 pistons, and 5003 with 3 pistons, had an easier time making back catapults than teams that only used 2 pistons.
If you only have 2 pistons, a front catapult is probably better for you as we found that our forward 2-piston catapult is able to get more full field shots than the backward one we tried. However, the advantages of more powerful backapults like 44 and 5003 is that the large ball is right on the end of the pivot bar as soon as you pick it up, whereas on a front catapult you have to lunge or have some special ramp to get the ball to the end of the bar.