Data Hoarder

QNAP only lists one TR-002 on their website and I can't find any evidence of more than one major version of the product. I'd guess that the -A-US refers to the power cable it's bundled with.

There are plenty of terrible products with a lot of good reviews on Amazon. The TR-002 reviews are pretty inconsistent and contradict each other on basic facts (e.g. some people claiming the TR-002 doesn't pass SMART data and others claiming it does - it does, BTW) so I wouldn't put too much stock in those. It's worth noting that this device can be configured and used in several ways, so it might be the case that, for example, it works great in hardware RAID0 mode but sucks as a basic port multiplier (as per my experience). I haven't tested the RAID modes personally so I can't comment on those.

All I can say is that if you have space for the drives in your case, have the spare SATA ports on your mobo, and don't have any particular use-case to necessitate an external enclosure, then you'd be mad to not install then directly in your PC. You'd only be adding cost and complexity for reduced performance and lower reliability. You may have noticed that a common refrain on subs like this is to avoid connecting storage via USB whenever possible. There's a good reason for that! You can easily end up with an unstable connection and random disconnects if the USB controllers happen to not like each other. It's always a gamble. SATA is far less temperamental.