I have this exact set. I cook with the lids and the come out perfect. I do use cottage cheese, but it’s blended in, so you done even know it’s there. Just tastes like fluffy eggs. I make a quadruple batch, using up the whole container. I freeze half of the completed egg bites for later use.
I always sub ricotta for cottage cheese in any recipe, as I don’t like cottage cheese either. But there are plenty of egg bite recipes that don’t use either. I generally use cream or half and half. I’ve added cheddar generally. Also once did a Swiss cheese with chopped mushrooms.
I’ve never made them with cottage cheese. I usually make with diced bacon and shredded cheddar at bottom and then pour on egg mixture. I cook with lids on and use a trivet in between for coming two at once. Never have had a problem.
Silicon lids are OK to use in the IP - plastic is not. You could also use foil for tops. The cottage cheese ends up getting mixed in - you really don't taste it at all, it's more for texture I think. Anyway, I'm sure you could go either way on that question.