Has anyone noticed any difference between the $100 adapter from SD and generic? I would guess that there are plenty of other commodity PATA to SATA adapters that would work for a lot less than $100.
Not sure, the replacement XL-Sata from Sound Devices isn't really an adapter. It's an entirely new ribbon cable with accompanying electronics that plugs directly into the main board, so I would think almost everything about is proprietary and specific to SD products.
In any event, I've been using mine for over a year and love being able to use a recent gen SSD. Really handy when you accidentally forget to bring an SD card.