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Did you try a print at a resolution of say between 100 and 150ppi? If you want to crop an image, or have an old low resolution one, then you'll see the difference I'm sure.
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I took a section of a 12Mpixel image I'm familiar with, equivalent to the whole being printed at A1 size, and printed that through the three programs. That would be roughly 120 ppi by my calculations. Printer was an Epson 3880, Epson inks and the paper was a smooth paper, not textured. While the images weren't absoloutely identical, there was no way to say one was better than the others. I know what I'm doing - I've been using Lightroom since the version 0 beta, Qimage from its first version, and versions of Photoshop from version 5.5 (which was truly dire at resizing for print!)