The compression caused by unmodified Duo Squat machines was a worry so I modified our two machines. The angle is much higher so makes them safer to use. I would modify the cam but it is a big job. It doesn't need to be so heavy at the end of the movement.
Vince, first and foremost, I really like your ideas concerning machines. I would love to own a duo squat, let alone a modified one, as Nautilus went too far when they made the leg press seat for the duo squat, which dealth with the spinal compression issue, but raised the spectre of knee issues with their machine (shearing forces).
Ideally, the duo squat would have an angle similar to yours, but with adjustable shoulder pads, and the back pad would have a lumbar "bump" so to speak to prevent unwanted "tail tucking" while performing one legged squats. But, that would make an already expensive machine even more expensive, and how could one expect the flotsam to buy such a thing?