checked out the S9 mask (auto function) and it is available. But here's the thing, with the auto setting the machine will just tick over while you are breathing normally, and kick in when it detects your breathing has stopped. The problem being that if you have frequent consecutive bouts of no breathing it may not keep up with the frequency of each bout, hence the need for a constant pressure to keep the airwaves continually open. This was explained to me by the experts ... So depending on the severity of your condition auto for mild or constant if your airways need to be opened throughout the night.
Obviously my heart condition required my airways be opened throughout the night, so I'll go with what was originally prescribed for me ...... But an update by our CPAP unit may be in order, since its been a few years since I've had one!
You may want to check out this theory for your own benefit, and I appreciate your concern and thank you for the advice. Also I'm looking into a smaller travel unit which I may invest in, they seem to be well designed and appropriately functional.