Funk - I've never had the pleasure of using one of these contraptions - what happens when you hit failure..? Are they far enough across to catch in a rack..? Spinal compression much..? You've got a helluva home setup - got anything like this..?
That Moore version looks dicey. I suppose you could get it up on blocks, and do a "buttom's up' squat if safety was needed. I've never seen anyone in real life go heavy with them, maybe at the most 2 plates a side. Looking on Youtube, this guy goes up to #345 on the Zane version -
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The Zane version is a little safer, not a great catch, but you could rack it and run -
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Edit, and just because, a photo of the one of the oddest squatting devices, the "Magic Circle" -

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