Haven't heard the old m120's but I have heard and own the Stereo 100. Most owners who have followed the Rogue upgrade path will tell you that the newer models are superior in SQ and much more refined than the older ones.
The ST100 has a completely redesigned board and voicing, so the old Stereo 90 and m120 will sound "different." If budget would allow you should step up to the updated modern models.
A few Rogue owners have chimed in on this on the Steve Hoffman forums. Hope this helps
https://forums.stevehoffman.tv/threads/rogue-st100-vs-st90-w-super-magnum-upgrade.574455/
The ST100 has a completely redesigned board and voicing, so the old Stereo 90 and m120 will sound "different." If budget would allow you should step up to the updated modern models.
A few Rogue owners have chimed in on this on the Steve Hoffman forums. Hope this helps
https://forums.stevehoffman.tv/threads/rogue-st100-vs-st90-w-super-magnum-upgrade.574455/