I haven't done the 1/4 windows yet, was probably gonna use the Calibri universal setup although I was looking for other solutions. The Calibri utilizes the existing regulator. It motorizes the door handle shaft. If I understand correctly, when installed you have to put a cap over the shaft that protrudes out from the door panel. Not too keen on that.
When I do find the right product, I have the OEM 4way master switch and two single switches when I get around to it.
On the main windows, they do not roll up as fast as they go down. They are affective and roll down faster than you could crank them by hand. I thought about welding lugs on the scissors and adding a helper spring. The modified assembly would load up on the way down slowing the downward speed and would unwind on the way up increasing up speed. Careful spring selection and attach points along the lever would be critical. I would probably try and dupe the originals. The original regulators did have springs, didn't they?