The DS series, no idea. Lights like Martin and Vari-Lite, they last for thousands of hours. It has a lot to do with how you take care of them as well. They movers I own, I baby. Clean them once a month at least, don't toss around, always give more then enough time to cool down after lamping off, try not to hot strike, etc etc.
Movers are just like anything else, if you take care of them, they will last you many years of service. Beat on them, and not as long. Martins and Vari-Lite especially are made to beat on. The Design Spot series from Elation, no one can really say as they really aren't that 'old' compared to the Mac and VL lines. What I hear however, is nothing but excellent comments about the DS line. Just no hands on experience with them yet. Soon, though, very soon I hope.