Depends on what you're printing to. We use X4 and RGB prints look best on one printer using one RIP software but CMYK looks better on a different printer using different RIP software. Raster images look better as rgb and vectors look better as cmyk or pantones. Takes a long time to get formulas worked out.
Myron
X4 by default is most likely converting the file when you print. Try setting the default to RGB.
Try going to Tools > Color Management and changing the setting to Color Management Off. I have trouble with RGB and CMYK all the time (usually it's RGB that looks better), and changing this setting can help.
One other discovery was that if I have ANY element of CMYK in a file when I exported as a press-ready PDF, the color would fade out and look terrible. One time I created an invitation and a matching envelope, and when they came back from the printer the greens were very different and I was able to trace the problem back to a single line of text that had been left CMYK.
It's such a strange problem and I have spent a lot of time trying to get Corel to play nice with colors. The suggestion above (first found on this forum) helped me -- all the best with your current challenge. :-)
Don't ever use color management off unless all you do is engraving, under the tools menu color management set the default to RGB as in previous versions. My color management books at www.graphictechnology.com answer all your questions