I am still not sure, why the Wii U VC is dropping inputs.
The more I look into SNES resolutions on PAL and NTSC systems, the more unsure if the topic I become.
(can a PAL game use the higher horizontal resolution of European PAL standards?)
Anyway, an emulator should create the same image as an SNES does in the end.
On a real Super Nintendo, the image of the game looks like it is mapped to the center of
of a higher resolution output, because it probably is.
And many Wii VC games do just that.
Since the Wii outputs 576i (or 288p?) in PAL50 mode, the result was the same as on a PAL SNES. 480 lines in the center of a 576 lines picture.
(actually it may 448 lines, I am not sure)
But apparently in the case of Super Metroid (or Legend Of Zelda, for example) the output is stretched to fill all pal lines.
There is no stretching. It's the original as-intended aspect ratio.
If you are referring to the aspect ratio of the final picture it may be the intended ratio.
I wonder what the developers intention was, when they created the PAL versions.
Would they have wanted to adapt their games more, but would not have enough resources/time?
But if you are looking at how the final image is achieved, it is being stretched, so the visible are of the game fills the height of screen. At least that is the case on the Wii VC.
And at least up close it makes the image look softer, because some elements bleed into each other.
by the way: I see that you did not reply to my explanation as to how the Wii and Wii U situations may be different.