Well, for me at least, the nasal pillows were a lot less encumbering than the FF mask. I think I'd have a lot of trouble getting used to that much strapped on my face. The pillows were a most welcome relief.
Also, if I can get my sinus clear enough to use the pillows, I think almost anyone can...LOL.
I've always been a mouth-breather too, but I do what someone on here said to do - I use my tongue on the top of my mouth to seal off my throat air passage. The cpap seems to cause a bit of a suction that holds it there all night. So...my mouth doesn't actually need to be "shut", which is welcome relief to my slightly misaligned jaw. I also don't need one of those chin straps - yikes, I really didn't like that (probably because it generated jaw pain to me).
I was glad to read on here that almost everyone has some problems falling asleep. There just something a bit unnatural about using a "breathing machine" to sleep. In my case, the ramping feature was actually keeping me awake. I need the full pressure to clear my sinuses and allow me to sleep.
For my first week, I could only fall asleep on my back. Not sure why, but it seemed easier to breath. It took some practice, but now I can fall asleep on my side with the cpap.
Oh, one thing you can also try if you are having a real problem are some sleep aids. My doc gave me a 1 month script for Lunestra and Ativan. Lunestra is an actual sleep aide (which I've only used twice), and the Ativan is an anti-anxiety drug (one of my probs was nervousness about being able to breath). Not sure what the Ativan (Lorazepam is the generic name) really does - it's a very mild dose, only .5 mg, but it did do the trick in making me feel more relaxed (though not actually sleepy, like the Lunestra).
If I've learned anything from reading on here, it's to stick with it. If one thing isn't working, try something else.
It's really worth it. Not only do I feel better, but I had no idea what an effect this would have on my wife. She usually ends up in the guest room half the time. Not only does she spend the whole night in our bed, but she no longer wakes up several times a night. I didn't realize I was sharing my sleep deprivation with her
Good Luck!