Five year later ...
All the research about quality and performance paid off. Five years later, none of the components failed except that a case fan got a little loose. After replacing the graphics card with a GTX 560 Ti and adding a 256GB Samsung SDD, the computer still feels plenty fast for software development, moderate gaming, and occasional image editing.
Update: I was too optimistic about the case fan - instead of just getting a little loose, now it's constantly making a loud rattling noise. It turns out that this is a common problem with this Thermaltake case, and I'm kind of lucky that I got the problem 5 years after purchase instead of 5 weeks. The current solution is to disconnect the fan and use HWMonitor to keep an eye on the temperatures. So far the temperatures of all the components are in the safe 40-60 ºC range under somewhat light load. If the temperatures get too high, I know it's time to build a new rig.