I can offer some anecdotal information based on personal experience. I have sleep apnea. I have used both the b-pap (modulated airflow) and c-pap machines. I prefer the simpler (and less costly) c-pap machine. It does work and it does help and I awake better rested after fewer hours in bed. My wife certainly prefers the hum to my snoring. For all of that, I seldom use it: I feel like an ostrich with my head in the sand, but my logic seems to be that since I am asleep when it occurs and don't remember the apnea episodes the next morning, I'll just leave it untreated. Dumb, but real. The mask/headgear seems the most important. Get one that fits well and comfortably, regardless of its cost. Consider a mask with the air hose leading out the top. Sounds goofy, but there is less tangling with bedclothes and less sense of claustrophobia. Good luck.
SIDEBAR: Although the systems do seem to work, I believe there is a kickback scam going on, at least in Reno, NV: The physician steered me to a specific vendor, that vendor rented the b-pap machine for 4 months at $600/mo, then my insurance paid 80% of an outrageous $10,000 charge to purchase the machine (yup, I got to pay the other $2,000 - about what the machine might be worth as a medical device). It just isn't that special; it's a fan with some logic driving it. I expect to read one day of an investigation into kickbacks throughout the industry.
In the meantime, I suggest going online to E-Bay and purchasing a used machine for 10% or less of vendor retail.
