The "uncompressed audio replacements" will be pretty nice, it will be interesting to see what comes of those.
There is a guy, Mathew Valente (a.k.a. TSSF), who put in a surprising amount of effort tracking down the original samples used by the composer of the SNES and PSX Final Fantasy games, Nobuo Uematsu. Nearly all of the samples came from various contemporary hardware and software synthesizers. Mathew found most of them (possibly with community collaboration, no small feat either way!) and took those original samples and remastered Nobuo's tracks. If you watch his videos, this was not a simple drag-and-drop operation, there is quite a lot of technical, musical, and subjective work and decisions to be made. The results are just beautiful.
I don't think this is necessarily good or even desirable, a lot of the SNES music was composed with the compression in mind and sounds off and weird when "remastered" like this.
Like this Pitchfork writer expressed it here about a classic SNES track from Donkey Kong Country:
Take one listen to “Stickerbush”’s fan-made “restored” version and you’ll understand why these compositional limitations are so integral. Here, the instruments appear uncompressed and reproduced through FL Studio. Wise’s wistful songwriting is retained, but completely missing is his intentionally impure palette. The instrumentation turns flat and unimaginative. Once-heavensent piano timbres are suddenly as ordinary as any run-of-the-mill ’90s new age track; the alto sax lead actually sounds like an alto sax, losing its unreal texture. Wise’s essential deployment of tension is absent without the compressed grain that elevates it. The idea of restoration is a “misnomer,” Wise said. He always meant for the song to be tethered to the restrictions of the SNES; he wanted to make limited sounds feel limitless. Like the comments section of the internet checkpoint, “Stickerbush” is a living time capsule.
For an example of a really horrible audio "upgrade", check out the Ninja Gaiden Trilogy (remake) on the SNES where they replaced the well-crafted NES instruments with SNES samples just triggered for the same notes and beats. Theoretically could have sounded amazing but is like nails on a chalkboard. Not apples to apples comparison with these SNES->SNES restorations of course.
They picked jazzy samples instead of actually thinking about how each track should sound. Many definitely deserve pipe organ, violins, harp, guitar or something better than horns. I don’t think the NES had real instruments it was mostly square/sine waves, but it was done in a way you could imagine the pipe organ, etc.
I suspect that for every game whose soundtrack was lovingly hand-crafted to take advantage of the SNES's unique abilities, you'll find 10 more that someone composed separately on a hardware DAW of the era and then someone else came along and tried to fit it into as a few bytes of ROM as possible.
Besides, there is no reason a remaster can't also add compression and other SNES effects in order to stay truer to the spirit of the original.
Super weird that they went to the trouble of finding all the samples and the output audio has noticeable lag in it. Compare to the original and you can hear it lagging in the 3rd measure. https://www.youtube.com/watch?v=JLrsUOA4Vb4
There is an example of that feature on the Modern Vintage Gamer youtube channel. See the timestamped link below. He has a whole video covering Super ZSNES.
There is a guy, Mathew Valente (a.k.a. TSSF), who put in a surprising amount of effort tracking down the original samples used by the composer of the SNES and PSX Final Fantasy games, Nobuo Uematsu. Nearly all of the samples came from various contemporary hardware and software synthesizers. Mathew found most of them (possibly with community collaboration, no small feat either way!) and took those original samples and remastered Nobuo's tracks. If you watch his videos, this was not a simple drag-and-drop operation, there is quite a lot of technical, musical, and subjective work and decisions to be made. The results are just beautiful.
If you liked classic Final Fantasy music, you'll love his channel. Here's one of my favorites: https://www.youtube.com/watch?v=XQhxNkZH-DE