There must be something to this idea of moving the XO away from the driver's into it's own enclosure.
I have another set of speakers, maybe 30 years old, with the XO hidden in a false bottom. I'm sure it's cheaper & easier to just mount it behind the drivers.
Tom you might be intrigued by this odd XO. It's all capacitors. No resistors, no coils. All drivers are selected to have the same sensitivity, so no need for resistors for shelving. Caps hi-pass all drivers so they have to be well-behaved above their normal freq. limits. And the woofer is a dual-coil unit with a cap feeding the 2nd voicecoil with phase inverted--to electrically cancel the high freqs driving coil #1.
I've never heard of or seen anything like it. The speaker is a brutal load from lower-mid-range upward because all (4) drivers are coming online, with no cutoff.