If there is a single panel in the engine, it will have colour separation artifacts.
The LED set I saw at CES 2006 was very good for colour separation but had awful grey scale performance.
CES 2007 the LED sets had better grey scales but at the cost of worse colour separation (so I am guessing that they slowed the colour switching to get better dynamic range at the cost of worse colour issues).
The other advantage LCoS (SXRD, DILA) has over DLP is that the native response of the LC is more like the desired gamma where DLP is exactly linear - so the LCoS has more effective low grey levels.
Keep in mind the I work in the displays so I am not necessarily unbiased.
That said I think DLPs are awful, mostly due to the colour separation artifact. If you can see colours for a black and white source, you can see this issue. So take your BD of Good Night and Good Luck when you shop for a TV
IMHO, the Sony SXRDs are the best RPTVs on the market today for overall picture quality (and no I don't work for Sony).