Passive bi-amping IMO, is not worth the effort.
You will not increase the dynamic range or prevent low frequency signals from impacting the high frequency response, as in active bi-amping.
One of the main benefits(maybe THE main benefit) of active bi-amping is the lack of a lossy, passive crossover network.
Adding a powered subwoofer and high-passing the mains would be closer to a true bi-amped system, and would absolutely dwarf passive bi-amping in its effectiveness at increasing the dynamic range and clarity of your system.