I thought about this for a long time, and it was the reason I didn't buy an X7 until maybe 1.5 years after the release.
My advice? Don't look at the knobs. Dial it in so it sounds good in the context of YOUR mix. Everyone says that mids are essential for bass if you want to be heard in a mix. I play in a death metal band (so that's two guitarists who think that more gain=more talent, and a drummer with lead feet) and my crossovers are about 200Hz low and 800Hz high, and **** me if I don't sit PERFECTLY in our mix.
That mid gap isn't as important as you might think.
Remember, the low pass knob doesn't determine what frequencies you're boosting or cutting, it only selects the frequency the *compressor* boosts (lower for more boom, higher for more finger-thump) and the high pass determines what frequencies the *distortion* boosts (lower for more fuzz, higher for more clank). In my band mix I've had great results with both high low pass (3 o'clock) and low high pass (9 o'clock), and low low pass (12-10 o'clock) and high high pass (12-2 o'clock).
And if you've got an active bass or eq pedal, no one's saying you can't boost your mids a bit