Buffering rolls with the C-stick is really weird at first, but once you get used to it, it definitely feels MORE natural. I learned it to make sure I could roll out of Marth's double fthrow @ 0%, and I'm slowly incorporating C-stick rolls into other parts of my game because being able to DI during rolls is mad useful, especially if you are playing characters like Peach or Sheik who will wreck you with dsmash as you try to roll away or something.
Other than that PP, I'd just suggest that you keep in mind that your path of improvement may not be the best. I say this because from all of your posts and game play, you strike me as a very systematic and disciplined person when approaching how to play a game. I would definitely say one of the things you seem to excel at is analyzing a part of your game play and then just expanding and expanding on it. I would even go so far as to say that's why you are really helpful to others when breaking down game play for critiques. However, to reference a
Sirlin article, sometimes the part of the game you are trying to expand is not the one best suited for you to win. Idk if that will really help you based on where you're at with your game, but whenever I feel stuck in Melee or any other game, my fool-proof way of getting around mental blocks has always been to just do something different instead of trying to do what I've been doing, but better. Maybe take it back to basics and question what you thought you knew about certain matchups, and hopefully you will find an unexplored part of the game that you can expand on that no one will have seen before (let alone be ready for). ^_^