Unfortunately, Furman makes many models and their feature set is confusing. The two key features audiophiles care about which your Furman strip lacks is SMP, and LiFT. SMP is series mode surge suppression, and LiFT is linear filtering. The PST 8 on the other hand adds those features: The noise filtering of SMP + LiFT is much better than without it, and the surge protection of SMP is simply outstanding.
If you read the description of the PST-6:
but without all of the advance features that the other Power Station products possess.
They mean it lacks SMP and LiFT. Look at the description for the PST-8, which calls out SMP and LiFT to compare.
I don’t really recommend Furman products without those two features.