So it would seem that the PQ can and will be oxidized by the high chlorine BUT the likely outcome of that oxidation is just smaller fragments of PQ not degraded biocidal activity. FC could potentially destroy the PQ but probably not until you reach some ridiculously high FC concentration that would likely never be found on a residential swimming pool.

Ok, you all have convinced me to close my pool using polyquat....oh wait, my pool never closes

Seriously though, I now understand PQ usage better so if I had a need for it in the future, like an Ascorbic acid treatment, I'd feel a lot better prepared about how to use it.

Thanks all for your insights!!