Interesting, I recently watched an Amos Heller video about one of the microbes X pedals where he said he got the best results by overlapping the high and low bands.I started off doing this but found that I couldn't get a good balance between the two. If I had enough lows to make the clean side work, the drives sounded thin, but when my drives sounded good, the low side was just rumble. I ended up ditching a traditional crossover and opted to split the signal and give each side a dedicated high and low pass. I found both sides really need to get a good amount of 100hz for the whole thing to work. I suspect that's why a lot of people have a hard time cutting through a mix with a crossover rig. I know I did.
Dude makes the best demo videos. I watch them repeatedly to listen to his playing, even if I'm not interested in the gear.