MiSTer FPGA GBA Splitscreen Multiplayer
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I may be somewhat biased here, as a significant chunk of my income comes from buying and selling retro games, but I think it's extremely rare to get a better experience through modern emulation compared to the original hardware running on a CRT TV.
There are a few exceptions where the developers actually made bad choices (Banjo Tooie is pretty much the only one that springs to mind; Rare put too much detail in and the framerate was unplayable), but overwhelmingly I find that developers were well aware of the limitations of the then-state-of-the-art hardware, as well as what displays consumers would be using, and designed the software with those limitations in mind.
SNES games with HQ filters, for example, are interesting and technically impressive but seem to lack some of the artistic cohesion and intent of the original software running on original hardware.
I understand that the original hardware will eventually die and that emulation will be the only way that these games are preserved, but at the same time I think it's best to preserve these as accurately as possible.
So it is much more like running original hardware like you've described than any other emulators.
I think it actually may be though. In terms of digital electronics, this IS the original hardware... But with added multiplayer. So unless the feature of multiplayer is a downgrade, then it is better in absolute terms.