I would go with Sphinx myself. Except the Sphinx was built correctly, ie a broader base than head. If you don't pick up a 5xx exactly right, it will tip forward and crack its commanding head wide open. From the back it sort of looks like a mausoleum crypt vault. Structurally, there is a reason it is more likely to be damaged during shipping ... it is a poorly engineered and an unwieldy design. I would be interested to know the statistics of the original damaged inventory during shipping, which in those days I believe was mostly handled by Apple which I'm sure exercised significantly more care than UPS.
Anyone who has Kunkle's Apple Design book can see pictures of the 5xx series prototypes, all of which blow the socks off what they ended up with. One of these days I'll get around to posting them. But it's clear, whatever you think about the CC, the Hook design was inspired by the CC and drew upon its unique features. It owes to the CC all of the good and none of the bad.
The biggest problem with the 5xx is that once those Macs get to that size, I would much rather go with a separate monitor and CPU which were easier to move around, ship and configure. The 5000 series improved the AIO design to the point that it all fit in the equivalent cabinet size to a monitor. The Power Mac G3 AIO tried to bee too much and ended up being almost as unwieldy as the 5xx. What barely saves it is good design and construction, despite the fact it looks like a bug molar. The iMac of course fixed all of that.
Just out of curiosity, If I was absolutely in love with the 5xx case design and wouldn't want any other computer sitting on my desk, would the contributors to this article be as outraged if I wanted to strip the logicboard out of a 5500 to upgrade my 580? Or is that just as taboo?