In general -8 is considered "unsafe", because you can neutral throw break.
However, it should be noted that there's more than just disadvantage to be taken into account for "unsafeness".
Kasumi for example has (and its variants) which is -12 on guard, but the push-back on it in open space makes it so no throws faster than 12 frames can reach her, so technically it is safe.
However, it should be noted that there's more than just disadvantage to be taken into account for "unsafeness".
Kasumi for example has (and its variants) which is -12 on guard, but the push-back on it in open space makes it so no throws faster than 12 frames can reach her, so technically it is safe.