I can bring an extra bag (have lots of them) - all this information has been very helpful. I did not realize that this did not count in the luggage allowance brought onboard. Need to get onto the CPAP on Monday and then many of my questions and concerns will be addressed by first-hand experience.

Thanks for the comparison and info. I was leaning towards the S9 which seemed sleeker, but it appears that the PR S1 is actually a better traveler in both size and ease. Whatever I do, I need to put this in my carry-on luggage and I carry a briefcase so a 3rd bag won't work. I was told however, when...

I am concerned about the portability but do not want to give up functions and features for this. Looking for others who have researched or know these machines or have direct experiences.