You are absolutely right - the original sound set sounded great.
I wanted to go beyond just emulating the originals as I think many will be surprised how different the original sources will sound. This is because the ST-01 samples were only snapshots of what were responsive complex synth patches. This is will actually make emulating the original sound very difficult in some cases as a single key will have to be played in the same manner as the original producer ie. same velocity, note length and FX processing.
The main object is to identify the original sources - this has become a bit of an obsession for me as synths built around the 1985 to 1988 era were very different to what we see now - The Roland D50 is posivitely oozing with character due to its low bit resolution, filters and use of PWM. These characteristics are almost impossible to emulate in a soft synth as the noise and aliasing from the old hardware becomes part of the sound. This is why, for example, 12 bit samplers such as the AKAI S950 are still favoured in making some types of music.
It's this character that made a lot of Amiga music so cool. Much the same is true for the C64's SID generated music as it too had a certain "sound" - quite unlike the horrible FM generated yuck that PCs were eminating a few years later from their Sound Blasters.