Well, I can say from demoing both over the years that most of the 3 chip DLP projectors I have seen have been better (IMO anyway) than single chip models. It depends on the size of chip used, lens and various other factors but generally speaking they tend to produce greater depth, more lumens, better contrast, colour and of course - no rainbows. Single chip technology will produce more consistent sharpness across price ranges and models but certainly the DLP chips in high end 3 chippers tend to be pretty tightly aligned so the sharpness is still excellent (or at least it should be for the price). Certainly the difference is there in real life.
DLP generally seems to have a perception problem (no pun intended). On/off contrast doesn't measure very highly and then there are people's reactions to rainbows. Then you also have the confusion surrounding different sizes of chips and the justification of cost differences - for example - the Acer 9500 and Sim2 Nero 2 are both 1080p, 3D, around 1000 lumens when calibrated, claimed contrast is reasonably similar and yet the difference in price is $23000
If you demo them, the difference would be pronounced and if you dig a little deeper into the technology you could understand why the Sim2 would be better. The differences, and positive aspects of DLP in general, are harder to convey in an easily quantifiable way to people reading reviews though.
I don't think we will ever see a 1080p Darkchip5, more likely we'll see 4k DLP if any new advancements are made.
As far as 2K DLP goes, I haven't seen any demos intended for home use so its hard for me to comment. Based on numbers alone, the Lumis should have better contrast but I am sure there are other advantages to a 2K model, lumens being the most obvious.