I've had a couple of DTS 6D units here for about 7 years. I've had one drive and one power supply go out. Otherwise, any problems I've had have been in the reader. I check the LED levels at the beginning of each season. Past that, there have been a few occasions where one reader or the other wouldn't pick up the time code without tweaking "the screw that voids your warranty".
Frankly, taking that label off and adjusting that screw is the only thing that's prevented me from sending in an otherwise good reader.
Overall, the DTS system has worked as well as my Dolby Digital setup, so long as I actually get (or otherwise acquire) the darned disks.