AA filter effects
Very interesting comparison between D800 and D800E which is relevant to the X-Pro1. See the following DP review comparison (taken from the D800/E review, recently updated):
The notable differences are:
1. False colour appears in the D800E tests, an inevitable consequence of using a Bayer colour array without an AA filter in place.
2. The D800 image appears blurred compared with the D800E image of the same thing.The easiest place to see this is the "Horizontal resolution" section of the page.
Most cameras sharpen their output as a result. Whether you like a sharpened image is a matter of personal taste - personally I prefer a more natural look.