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
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