I have always had trouble breathing through my nose, and for me the pillows system has not only resolved that issue at night, but has actually worked to allow me to breath through my nose during the day as well.
That said, if the pillows mask all by itself did not allow me to sleep comfortably (without any rinses and sprays and whatsits -- the only thing I want to do at bedtime is discover my pillow....) I would not hesitate to go back to a full face mask. I'd probably try the Resmed F10 mask. Maybe others. But the one thing I can absolutely say with perfect certainty is there is nothing that would "kill my desire to keep the Cpap."
In the interests of your health and perhaps the health of others it is important to no longer look at this therapy as something you must bear.
Embrace the possibility that you too can have an improved and longer life now that you have been given this blessing. If this mask, or that spray, or whatever gets in your way of doing that, find another way.
First of all, your pressure sounds really low to me. At 5-6, I would not be a happy camper. My pressure minimum is 10.6. That might be a little high for you at this point. Do you have any test results that indicate what your pressures should be?
As to the congestion, all I know to tell you is what I have often said, which is I am the poster child for not being able to breath through my nose. I have always been a "mouth breather" because my nose doesn't work right. Deviated septum? Yeah maybe, but it's not anything I have ever wanted to go see Mr. Doctor about. Just has not sounded all that fun to me. Anyhow, I started my therapy with a nasal mask, then migrated to a full face mask. After wrestling the leaks for awhile, I asked for a pillows mask. "Ok," says the DME guys, "but what makes you think you can breath with it?" It was my great pleasure to learn that when I used the pillows mask I could not only breath with them, but they actually helped to keep my nasal passages clear.
I use the Resmed P10. I used the swift for awhile, but I like the P10 better because it diffuses the exhaust air so well.
One thing about the pillows which you may have already discovered: If you have one that doesn't seem to be pumping air, or is leaking, lift the pillows gently off your nose and let them resettle. That takes care of the majority of pillow leak issues.
As to my nighttime regimen? I ask/answer three questions:
1. Is it dark? (Yes)
2. Am I sleepy (of course)
3. Am I laying down on my comfy bed cuddled up in my covers with one of the puppies beside me? (If no, then why not?)
Short of making sure my machine has a full jug of water in it, I do nothing else. No wash face, no brush teeth, no nothing. No how. Just put on my mask, lay down, and wait for morning. I do "jammy up," but that's usually taken care of before time to go to bed.
Anyhow, investigate your minimum pressure setting. Maybe you belong that low, but I know if that was me I'd be thinking I couldn't breath good and should do all sorts of crazy go nutz things to try to make my poor little air starved nose work better.