turkey3_scratch :
I also find it funny their "500W" power supply supports cards up to 375W.
Technically, 375W is the maximum that would be theoretically possible for cards that follow the PCIe spec: 75W from the PCIe slot + 2x150W from the 8-pins PCIe connectors.
Then you have the Thunderbolt/USB hub, the Ethernet port, fans, other connected devices and possibly other stuff eating another 50W or so.
I do not see why you are so skeptical about the quality of the PSU. For the most part, the difference between a crappy PSU and a very decent one is simply switching the caps from Fuhjyyu to Nichicon/Rubycon/United Chemi-Con/Panasonic/Epcos/etc. Upgrading the caps only adds something like $2 to manufacturing cost to make the PSU last over three times as long. Out of that $500, you have maybe $100 for the PCIe-to-Thunderbolt bridge, $100 for the fancy enclosure due to low production volume, which leaves $300 for profit and the PSU. A top-notch 500W PSU costs less than $100, which leaves them with over $200 in gross profit margin per sale.
Also, if they put a crappy quality PSU in an enthusiast-oriented device, they will get a bashing when someone eventually gets around to doing a tear down of the thing.