I Guard Impact quite a lot, even though the opponent isn't gonna do anything. I just do it out of anticipation instead of reaction.
I heard the Guard Impact in Soul Calibur VI is similar to Soul Calibur V, the only difference is that it won't rely on meter and it's 6G instead of 4A+B+K. Yep, only one type of Guard Impact instead of 2 types like in Soul Calibur II or 4 types like in Soul Calibur I, III, and IV (if Just Impact counts, I guess that's 5 types).
6G repels all hit levels (highs, mids, and lows). All you need to do is catch your opponent's timing instead of reacting/anticipating on what move is the opponent gonna do, whether it's a high or a mid or a low. That's how Guard Impact was in Soul Calibur V and that's going to be the same in Soul Calibur VI. Aaaaand I also heard that it has a lot less frame advantage.