JL Audio subwoofer crossover - any comments ?

I currently own a JL F110 and I was thinking of adding another F110 ....I see where JL Audio now has a crossover for sale and was wondering if anybody has purchased this product and has it helped in integrating their subs in a 2 channel system ???? I have always thought that a crossover is the correct way to go when adding sub-woofers to a music system. Thank you in advance