I have to go into a little more detail.
The most known Sond Canvas devices after the SC-55 are:
- SC-55mkII - which raises the maximum voices (polyphony) from 24 to 28
- SC-88 - which raises the maximum voices frin 28 to 64, the output resolution from 16 to 18-bit and increases the number of tones (instruments) from 317 to 654 and the drumsets from 9 to 22)
- SC-88Pro - which raises the number of tones from 654 to 1117 and the drumsets from 22 to 42
- SC-8820 - which raises the output resolution from 18 to 24-bit, the number of tones from 1117 to 1608 and the drumsets from 42 to 63
- SC-D70 - which is basically an SC-8820 but with digital in- and outputs as well as raising the output resolution from 32kHz to 44.1/48kHz
Each unit comes with new instrument maps, which replace some of the older instruments, so some of the instruments might be the same as the old one while others may have been changed. And all contain the maps of their predecessor. So SC-D70's main map is the SC-8820 map but it also contains the maps for the SC-88Pro, the SC-88 and the SC-55. The music packs will be recorded using the SC-8820 map.
So in short: Many instruments will differ in comparison to the Roland SC-55 and the output resolution is a lot better, which will result in better audio quality. Whether you like the music packs more with either the SC-D70 or the SC-55 is personal preference. There are some instruments I prefer from the SC-D70 (e.g. brasses in D_E1M6, it just sounds great), but I prefer some of the synth basses from the SC-55 (e.g. D_E1M3). The Roland SC-D70 offers a lot more variations though (more instruments), but not many MIDIs actually make use of it.
More detailed information can be found here:
https://en.wikipedia.org/wiki/Roland_Sound_CanvasAbout the continuation of the music pack:
Before I will add other games I will release a V2 of the existing ones, cause the current version does not contain any loop points metadata.