I have the stg 3 with an aluminum flywheel. I didn't like it at first because it was overly grabby, but now its fine. It still grabs hard, but is managable. So far so good...
The "soft" can also be "light." It means that it doesn't take a lot of effort to push the pedal in. I was a serious doubter about the Spec stg1 with pedal effort - it was my biggest concern and when the guys at the local shop were telling me that the pedal effort was lighter than the KC, it almost ruined their credibility with me. They were totally right. My guess is that they must set the fulcrum on the pressure plate closer to the center and increase the rate of the springs. At any rate, the pedal effort is lighter than the KC. I just drove a Spec stgIII car and it was even lighter than my stgI - go figure