Gotcha. I understand.
By all means try a nasal interface mask that interests you. If there is no physical reason to just have to use a full face mask then there is a real good chance that you will have success with a nasal mask and for some people it is simply a lot easier to get comfortable with and sleep with because the nasal has such a smaller footprint on the face.
Often dry mouth is associated with mouth breathing but not always and even if it was there's no proof that the mouth breathing is so bad that it seriously impacts therapy unless someone evaluates the leak reports in great detail.
Someone took the lazy way out with you...you mentioned dry mouth and they said "oh, mouth breather so you have to use a full face mask" and they didn't bother with letting you try other masks or even making sure that the therapy might be impacted or not by mouth breathing.
When you have time read this from Perrysbucsdad
viewtopic/p663440/Mouth-Breathers.html#p663440
He also originally thought he had to use a full face mask because he had a bit of a deviated septum and someone told him that he couldn't use a nasal mask. I had to just about twist his arm off to get him to at least try a nasal mask. Once he did though...the rest is history.
I mouth breathe on occasion. I know I do because I wake up with a bit of a dry mouth and I am mouth breathing.
Mostly it's out of habit though...my nose is fine and not congested and I am usually on my back when it happens.
I don't spend much time on my back because it causes back pain to be worse...so if I do mouth breathe it's never for very long and often it barely even shows up as much of a leak on the leak graph.
I am NOT going to wear a full face mask for 15 minutes of maybe mouth breathing leak because for me a full face mask causes more sleep disruptions than the 15 minutes of maybe mouth leak might cause.
I don't know that a nasal mask will let your sleep be more consolidated but it might and "it might" is surely a good enough reason to try something.
As to which one....dunno but I always tell people to go with what looks interesting to them...gotta start somewhere and what looks interesting is a good enough reason as any.
If headgear sort of bugs you...go with a nasal mask with minimal headgear. If venting noise bugs you...go with a nasal mask with diffused venting.
I may have to RISE but I refuse to SHINE.