Another thought about venting to the outside. They have these heat exchangers to bring in fresh air to houses that are REALLY well sealed. I have no idea of a heat exchanger could handle the CFM of a dust collector. I kind of doubt it.

Another possibility is to put your collector outside in a little shed attached to the house. The air gets sucked outside and then vents back inside through some additional filtering. Now you lose less heat/ac and you don't put up with the racket and you get some space back.