I almost bought a Dwin Transvision recently, based on a demo I had seen in a local store. It was clearly the best of the DLP projectors I was able to see locally, but I wasn't able to see many projectors in person. I can't say anything useful about the rainbow effect... I don't seem to be very sensitive to it.
At the last minute, based on the buzz in this forum (and some advice from the AvScience folks), I decided to get the Seleco HT200DM. It was a blind leap. I wasn't able to demo the projector, but I'm very happy with that decision. I can't do a complete A/B comparison because my HT setup is a little different from the store where I demo'd the Dwin, but the Seleco seems to have a better picture, with deeper blacks, better reds, more "punch" to the image.
The other thing I really like about the HT200DM (which I assume would also apply to the Sharp 16:9) is that it has almost no extraneous light leakage around the image area. That was the one thing that bothered me about the Dwin when I saw the store demo. There was a large, fairly bright area of light leakage (overscan?) above and below the 16:9 image area. It was very distracting. This doesn't happen with the HT200DM, or any other 16:9 projector. The light from the projector just stops at the edges of a 16:9 screen. It's a much smoother presentation. You don't have to go nuts trying to mask off the lens or screen area, or mess around with contraptions like a Panamorph lens.
The Dwin is also priced too high. The price would have made sense a year ago, but there are better DLP projectors out there now at cheaper prices, and more evolved high-res native 16:9 DLP projectors are starting to become available.
The Sharp 16:9 sounds very nice, especially with the recent user reports. If I was shopping right now instead of a month ago, then I might wait for it. However, the new Sharp has only analog component inputs, which may be down-res'd to 480p under the newly announced industry schemes for "premium content" (which basically revolves around PPV movies and time-shifting HDTV with a PVR). For more info, see recent discussions in the HDTV forum here. That's the only downside I can see to the new Sharp. It would be a shame to spend in the neighborhood of ten grand for that projector, and then find out a year from now that you couldn't watch high-def movies on it, or use a HDTV PVR with it. On the other hand, if you're only interested in DVD movies and don't care about HDTV, then it may be a terrific projector for that purpose.