Yes, I don't think a lot of people realize that it's possible to run the AirSense 11 (I don't know about other models/brands) without distilled water. Resmed even sells "ResMed AirSense & AirCurve 11 Side Cover", which takes the place of the water tank.
My humidifier broke years ago and I haven't bothered to replace my unit. It gives me a little extra space to sneak a few more things onto flights by stuffing them in the CPAP bag where the humidifier would go. (I don't remember what model number I have, it's ancient, but the humidifier is easily detachable.)
