I don't think it was Borresen's intent ever to be a "more affordable" brand.
The X series was probably a more temporary offering to get their sound in the hands of more individuals and get them talking (get the hype up)....because there's not much of a sonic difference between the X's and the higher models I've heard if you equalize the electronics.
The higher models sounded better because they had their flagship electronics tied to it, no real miracle of the speaker.