You've had a lot of answers but I am going to post another, as well as an international travel experience.
I used to travel with my Airsense 10, with humidification. While it is true that in the US, a medical device does not count toward your bag allowance, that is NOT always the case internationally. While boarding a plane in Scandanavia, I was told that I had to pack my CPAP or my small (very small!!) crossbody bag into my suitcase. I explained it was a medical device. They said that was fine, pack it...only 2 bags, PERIOD!! I bought my AirMini when I arrived home.
The AirMini, packed in my little Vera Bradley lunch bag, is less than half the size of my Airsense carry case. I am able to use it with my Bleep (I hacked the hose. I carry it easily in either my carryon or purse and do not need to have 3 bags. In September, we went to Egypt and I put in it a backpack, my ONLY carryon, which contained my CPAP, meds, 3-1-1 bag, change of clothes, Kindle, and chargers. No way could I have done that with my Airsense!
It makes sense for me, because we travel internationally at least twice a year, 2+ weeks at a time. In addition, I/we take other, shorter domestic trips throughout the year, ranging from weekend through up to a week.
That said, my husband travels with his Airsense 10, no humidification. It is always his only carryon.

Everyone's needs are different!