A while ago, someone here posted the song "Brown Sugar", played on an Casio WK 3000/3500.
Since I have the midi file, which was made by Roland if I am correct, I downloaded HyperCanvas and used is to replay the song.
I was able to do a side by side comparison of sorts, playing it against the mp3 by Casio.
HyperCanvas seems to have "crisper" sounds (claims 26 MB samples linear equiv), although not that far better in quality compared to the Casio.
Casio seemed to have better, more "beefy" bass, but the leads used, were weaker. Also, Casio seemed to have a lot more reverb and also the line noise was noticeable.
I suspect the GM/GS midi, played straight through the Casio doesn't do it very much justice, since individual instrument levels are different and should be changer accordingly.
Anyway the HyperCanvas seems to have better sound overall.
I tried some other midis, also made by Roland, "Careless whisper" comes to mind... It was almost identical to the "real" version, until the sax line came in which was not enough.
Are there better GM softsynths around?