DLP is a great technology, it's the spinning color wheel that causes the rainbow problems. If LCD or rLCD (AKA LCOS, AKA D-ILA) used just one chip and a spinning color wheel to produce color, the same problem would result.
In fact, a company in "Home Theater Interiors" is developing a single chip LCOS ("D-ILA") with a color wheel. Bad idea, IMO, but it shows that it's not just DLP that may have the rainbow issues.
Three-chip DLP projectors are absolutely beautiful, and don't have any image artifacts that I can see. Unfortunately, they are really expensive (for some reason, they are a *lot* more than three times as expensive as a one-chip DLP).
I understand that the rainbow effect is minimized by the faster wheels, and the wheels with more segments, and the wheels with the spiral patterns. We are just starting to see projectors with some of these improvements, and the archimedes wheel is probably a few years away.
Anyway, I apologize if you already knew all of this. I just wanted to mention that there is nothing in the DMD chips (DLP) that cause rainbow...it's the color wheel that causes it.