I think I'm one of the few who had a DPX-1 and now have the Sharp 9000. Let me tell you the main differences, in my opinion:
-The Yamaha is not a true HD projector. Programs like the Winter Olympics on NBC will look much better with the Sharp. The Yamaha is a native 4X3 and loses resolution if you use it on a 16X9 screen. If you have the dough to buy a front projector at these prices , why keep watching only 4X3 and ignoring the beauty of High Def programs???
-The colors on the Sharp are much better. The Yama always looked a bit "washed" to me.
-I don't see rainbows at all and don't want to see them. But my wife does, only with the Yamaha.
-Because the Yamaha is a native 4X3, there is a lot of "light spill" when using a 16X9 screen. The "halo" is about 25% of the whole picture and is VERY annoying.
-The internal scaler in the Yamaha is better than the Sharp. S-video will look better with the Yamaha . I don't use S-video with the Sharp , but if you have to it will be worse than with the Yamaha.
I am very happy with the Sharp and I never was with the Yamaha. I agree with people that suggests you should buy a cheaper projector instead if you really want to watch only 4X3. Otherwise, go for the Sharp or Marantz.
Sergio