Joel, i think you don't understand how the 950 handle the subwoofer signal, when you set the low cut frecuency for a speaker group all the frecuencies from that point are routed to the subwoofer, so threre's no giant hole in the low frecuencies if you have different low pass settings for each speaker group.

In every case the subwoofer handles the .1 signal if present in the source, tha signal it's routed to the subwoofer no matter what setting you have for the crossovers, except if you don't have a subwoofer at all, in that case the .1 signal is routed to the main speakers.