I guess I ended up with some reasonbly professional folks the two times I went in for sleep tests and machines. This last on I got recently, they went over the machines and which one they and the dr. had decided on would be best for me and why. Then I spent over 1 hour in the office going through mask options, trying several, picking what we thought would work best, getting fitted, doing a mask adjustment, mask leak test, trying several masks. Before we even started talking masks they wanted to know how I slept (back, side, stomach etc) and another 20 minutes going over all the features of the machine, what I was able to adjust or change, what the effects would be etc.
End result. first night everything was "easy peasy" and worked great. No fuss, no muss, minimal adjusting.
Only thing I ended up changing was that the front of the headpiece was soft plastic. very comfortable, but in the morning the side of my face I slept on looked like I had a Nike Swoosh tatoo. Gave them a call about a week later and they replace that portion with a fabric part. Not as comfortable, but no more Nike Swoosh in the morning.