I checked on Amazon for the Thermaltake dock and while there are a number of people that rave about it, there are also a number of reports of the dock stop working in 1-3 months. In all of the post I have read on here, no one has ever mentioned the BlackX dock stop working. I realize its mechanical and all mechanical things can fail but just curios if any of you have had to replace the dock?
I've posted about this many times in several of the overly long eSATA threads. I don't expect anyone to actually read all the posts on those threads, too many, too confusing and as you go back the threads are filled with outdated information. But to address your question: Yeah, they do fail. Like most of the external devices they're cheap to buy and cheaply made and their performance suffers from the cheapness. The TT docks have always had one glaring weakness, the on/off button. Simple way to deal it? Don't use it. Use it and you'll find your dock will go dead when the button fails. I've had this happen several times. And to top off the problem, you can't jump the switch out so that it stays in the on position all the time (I couldn't figure out how to do it, anyway.) If you have to shut the dock down, pull the power cord rather than using the on/off switch.
Aside from the on/off switch, there is the problem of seating the HDD properly. Use a flashlight and examine the connector inside the dock. You can easily see how to properly seat the HDD. Put more simply, you can't just drop the HDD in the dock and expect it to work, the HDD needs to be securely seated. If you can easily lift the HDD out of the dock, you're not seating it correctly. You should expect the dock and HDD to be locked and if the HDD is lifted the dock should follow the HDD.
Once you get a dock working you can expect many hours of use from it. They really don't just fail.
Hope that answers your question. We've always recommended the docks because of their simplicity. Other devices (also cheap) have fans in them and that's just another point of failure. I've never had an HDD adversely affected by a dock, no dust buildup, no heat issues.