My feeling is much like many things. The almighty dollar. It’s cheaper and faster to produce and adjust the u-Chanel model.
Just stamping
and bending them was much cheaper. The bend alone made them really strong.The popsicle sticks we're hard to adjust because of the little snap rings they used on the pins.
Especially after they were on a few years and were rusted. It was almost impossible to get the snap rings off the bottom pins on a Max II.I always got rid of the pins and used bolts with lock nuts.
The only problem with the U-channels is they didn't make a place for them to pivot on.
They just let them rock on the transmission case.It works but not a vary smooth transition.
That can be fixed without splitting the case.
This up grade will also help pull the plungers straight in and out and not push or pull them to the side wearing out the O-rings.
I also use a hacksaw and cut a slot for a screwdriver in the head of the bolts that go into the plungers
then you can make your adjustments with only a screwdriver.