Whew, current 1070 owners can sigh in relief.

The thing that keeps it so consistently good is twofold. Until $2000 LCoS and similarly priced high-end LCD drop their prices in half, DLP will always have a huge contrast advantage at this price..while there's no way to significantly improv DLP contrast (besides putting a second chip into the single lightpath), there's also practically no way to make even a cheap DLP have significantly worse contrast, so cheap and expensive ones all have roughly similar contrast to a decent professional cinema.
The second part is that the w1070 happens to be a particularly accurate RGBRGB style DLP which has sadly become a rare thing despite it literally costing nothing more to make and obviously performing better than the competition because of it.
If you can get away with losing some brightness and 3D, the LG pf1500 is a LED DLP that may offer a little more longevity, though it sounds like the w1070 held up for quite a long time too. Any respectable LED unit should last 15,000-20,000hours, but the pf1500 costs about $300 more than the Benq and also loses some placement flexibility as well as 3D and a decent chunk of brightness to start.
For the price of the w1070, it's really hard to match even including lamp replacement prices.