Vantec/NexStar can do UAS; you just need a working cable
I purchased a 2-bay NexStar USB 3 to SATA III dock. Initially I was disappointed because I had to disable UAS under Linux. When I went to use it under Windows I discovered Windows doesn't have the option to disable UAS, but I after much searching I found a hint on a Microsoft forum that Vantec is actually pretty good about customer support, so I contacted Vantec customer support. They (correctly) said that UAS should work and the problem was either the cable or the dock itself, and suggested testing with another cable to determine if the issue was the cable. It turned out the issue was in fact the USB cable, so they sent me a replacement, no questions asked. I am only giving four stars because the initial problem is the choice of use a too 'cheap' cable supplier, but they do make it right.