In preparation for travel where I wanted lighter camera and a camera that if stolen from my hotel room would not hurt as much, I decided to resurrect my 300D.
Obviously for most travel pictures, which are printed at 4x6 and placed in an album, any old camera, even a P&S would do. But the question I had was what about the few pictures that were worth blowing up to 12x18 and framing. Would I regret not having my 5D. So I decided to test both in a touristy scene.
I used my trusty 70-200 f4L and a sturdy tripod. The first picture with the 300D was shot at 70 mm. To keep the field of view the same the second picture with the 5D was shot at about 112 mm. Both were shot in RAW and converted to JPEGs using DPP. Settings were set at daylight and the picture style at landscape, a typical touristy setting, and neutral. All other parameters were set at 0. Exposures of both were perfect so the only post processing was to add a bit (the same amount) of USP after resampling. Both were resampled in Photoshop CS to 8x10 350 pixels per inch using the bicubic algorithm, then printed at 8x10. The image from DPP was then resampled to 12x15, USM applied and printed.
Impressions: I really could not make out any differences at 8x10. Even at 12x15, the differences were small.
I have uploaded the images just as they came out of DPP for anyone who wants to repeat the experiment.