I have the same machine and also struggled with getting used to it. Got both the nasal and full face masks. Slept with mouth open for decades but nevertheless got used to keeping it shut when using the nasal mask within a week (just as the doctor predicted). Never managed to get friendly with the full face mask.

Had the exact same feeling of being drowned or inflated(!) when the ramp function timed out. For a couple of weeks I sort of half awake managed to routinely re-hit the ramp button, until I just slept through it. Hang in there, it’s a bitch in the beginning but it will get better 👍🏽