Originally posted by tabl10s if you never intend to print? I highly doubt I will.
Assuming it's modern sensor tech and pixel QE, more MP gives you 1) ability to print or display larger while maintaining high DPI/PPI, 2) better cropping ability, and 3) more appealing high-ISO images when downsampled to the same display sizes.
By 'more appealing' I mean: the noise is finer-grained, and when downsampled tends to give an image that looks crisper, nicer, more 'real' than the noise footprint from less MP. It also tends to hold up to NR better while preserving detail. You can also see some of this effect with lower-ISO images. (The downsampling benefit is kind of a big deal, because more people display on the web at 1024, 1600 or 2048p-width than print these days, and more MP can help there.)
Downside: Diffraction will give you diminishing returns a bit sooner (but will never produce an image with
less detail than a lower-res sensor, a point some get confused about,) and the files will be somewhat slower-to-process until your workstation is upgraded to match.
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