2010: Realizing the OP has moved on. I owned both and at the same time. To clarify, I owned the DCS Purcel and Delius and the EMM Labs CDSD and Dac6e combo.
Both are wonderful and are more alike than different. The differences that does exist are not significant (like night and day) but are different by shades.
Firstly, I think both are smooth and very well rounded devices that are not typically going to offend too many people. Not everybody will find they are their cup of tea, but I would be surprised if anybody can really say either offends them.
The EMM Labs is perhaps a hair warmer sounding than the DCS. The DCS is not analytical, but ever so slightly more detailed sounding - but both offer plenty of the details. I have also owned Wadia, Esoteric and other good CDP/digital front ends, but am just answering the OP Qs.
Personally, I would not exchange one DCS for an EMM Labs of the same vintage as I do not feel that the difference between the two will significantly change your sound, improve or otherwise. I think the DCS components are a bit more reliable than the EMM labs, which I fear are a bit more sensitive (but I never had a problem with mine when I owned them - EMM Labs that is).
Both loose their value significantly vs. new when newer models come out and based on the initial selling price. Both are much, much better values used and can be purchased for WELL under 50% of the new price.