I semi-agree. it depends on drivers. But, from experience, if you wish to play your music loud and still have SQ, your gonna need to HP a little higher for your midbass drivers. I have Hype-R's in the front, said good till about 60Hz, but at higher levels with all EQ's off, they still distort due to physical limitations vs. power. UNCLIPPED mind you. It can reproduce those frequencies, but not at full amplitude. If you HP them at 100 or maybe higher, you can easily get them to play cleanly until you hit clipping or full power.
If you do not go for loud SQ, then you can HP them at 80 and you'd be fine for most music at medium listening ranges, and benefit from a little mor midbass.
When I get the sub in, it will be 100HPF on my speakers, and 125 LPF on the sub. This way I'm getting no distortion from my Mid drivers at high volumes (this is tested several times now) and my sub can overlap my drivers to ensure nice reproduction.
Of course, I need the sub in to finally tune, but those are my plans.
~Levi