Do I need both sets of ventilation holes?

[Coffee Man]

I can use a small or medium N30i cushion but a large P30i cushion. Everyone is different but you really want to use the biggest size P30i cushion that fits without causing significant leaks. It might be reasonable to order a medium and a large cushion and try them both. You might end up paying for a size you don’t need, but if you find a cushion that works for you it would be worth it in the long run.

[Benzi]

Thank you, thank you, thank you for recommending the P30i cushion! It arrived yesterday and it's a completely different experience. I can lie on my side without feeling that the pillow is pushing against the side of the nose piece (because it's soft), the seal is good without needing to make the headgear tight.
For some reason the air seems warmer but I guess I can get used to that. And my wife didn't hear anything!
G-d bless you all for your advice.