I don't know that the increase in bass damping of the main speakers would be much of an issue since you are wanting to remove the bass from them anyway. But, I guess you are saying that the bass they would still produce would not be as well controlled as without the passive filter.Yes, exactly. And with an 80Hz high-pass, that conceivably could even be first-order (6db/octave rolloff), bass damping and back-emf control would still likely be a very significant consideration.
Best regards,
-- Al