I've been researching a windows tablet, because I now have a potential need for a simple device running full windows (it's to interface to a sensor).
If it's an atom powered tablet, USB 3.0 is kind of overkill. The SSD speeds are not much faster than USB 2.0 so, as such, it's not a major bottleneck. If you're watching videos directly off the HDD, then you don't need huge speed at all.
I've also had a look at USB power, and I've similarly read that a few have issues with power output to run devices. Generally HDD's need additional power, from what I've been reading. It's a bit of a bummer if they normally work properly from correctly powered USB ports.
The thing that has bothered me the most is, the Thinkpad 8 would have probably been ideal for me, in my desired application, but since it still is a computer running full windows, 2gb ram is quite low. There are 4gb models in only some regions (not mine). But still, have read that that they have quite a few problems with poor battery life, and USB OTG not working.