I still have not heard 1 solution to the 4 player multiplayer issue with Max 4 party size. More than anything else, if they don't increase party size to 6, Multiplayer with 4 people is severely limited and you can't enjoy all aspects of the game.
And every time someone says, "You have SO many people in your party already," I just wanna laugh. 4 people is OH so many. [Sarcasm] Come on.
Sounds like Composer and I are on roughly the same page.
Option
1. 4 party = everything as is for you "Please don't change the game" folks.
2. 6 party = D&D 5e stats and rules and XP rewards.
Slight homebrew is usually necessary. Totally get that. Especially boss monsters. What fun is there if you don't throw a nasty homebrew boss in here and there. Phase Spider Matriarch is perfect example. Don't mind her having special powers. Teleport around, spitting poison. That's good for her. Not for her minions.