The reason low crossover points are being recommended is because most sub manufacturers expect their clients to run the sub without a high pass filter on the main speakers. They are trying to bring the sub in under the main speakers. It is also much less noticeable way down and easier to integrate without screwing things up. You also have more flexibility in placement. But the improvement in distortion levels coming from the woofer more than make up for any disadvantage particularly with smaller loudspeakers that use the woofer as the principle midrange driver.
Your LS50s will grow to three times the size.
Your LS50s will grow to three times the size.