If you make prints you wont be showing them to anyone who will see a difference or give a cr@p what you took that LOLcat photo with.
I print a lot of images from my 1D4 on A3 (about 16x12) which needs a crop from 3:2 to 2.828 :2 (not much)
The most important aspect of those size pictures is lack of blur, either through OOF or camera/subject movement.
Next down the list is noise, followed by lens softness
Last on the list is DR
Modern camera technology advances has switched emphasis from mps increases to ease of getting a well exposed and focussed images and improved optics to allow more people to get top IQ - a switch from a black art to a consumer capability
I would think that this applies to most 'standard' pictures
There are of course times when all IQ aspects have to be first class (excellent) such as in fine art. However when printed the limitations of the printer are hit first - hence the latest improvements in print technology which are striving to keep up with camera technology.
The most cost effective way to improve your images is probably a top of the range printer with multiple black inks.