Your list is pretty solid. Here are the big things I disagree with, though:
1. Puff needs to be in S tier. Puff has literally been winning supermajors. And her matchups are great. I would say Fox vs Puff is roughly 60:40 Fox's favor, and that's Puff's only bad matchup. And unlike many other high tier characters, Puff doesn't have a lot of neutral matchups. Falco and Marth are both even-ish matchups for Puff, but after that, Puff Sheik is ~60:40-65:35, Puff Peach is 70:30, Puff Icees is ~70:30, Puff CF is ~55:45... I could go on but I think the point is clear. Puff wins almost every matchup. And with all the advancements Hbox has been making in the Puff vs Fox matchup it's hard to believe she even loses that.
2. Peach should be lower. Armada has everybody fooled but Peach actually isn't THAT good. Beyond Armada, the best performing Peaches are only placing comparable to the best Falcons. I think it's fair to say that MacD and S2J are equal in both skill level and tournament results. Further down you start getting players like DOH, Bladewise, and Kalamazhu, who are comparable to n0ne, Guts, and Wizzy. The fact that the results and skill level are so comparable between the two isn't a coincidence - Peach and Falcon are comparable.
1. I agree. I just hesitate to consider Puff S tier when Hbox is really the only player making progress with her. When comparing Puff and Fox for example, there are many mid to high level Fox players that are all placing well and playing the character in a unique way. In my opinion, Puff players besides Hbox aren't noteworthy. There are so many great Fox, Falco, Sheik, and Marth mains outside of the top 6 I could think of, while with Puff not so much. The characters I put in S tier have potential and consistency that Puff, Peach, and the rest just don't have.
2. Again, I agree with you. Peach and Falcon are definitely comparable. The main reason I placed Peach higher than Falcon is because of how their matchups with S tier characters compare. From what I've seen, Peach fares much better against spacies in particular. They have a much harder time comboing Peach, and edgeguarding Falcon is a breeze while edgeguarding a Peach with good mixups can be tricky. Overall, I think Peach has a better place in the meta, and the way I think about it, while Peach only has Armada as a top 8 placer, there really isn't an equivalent Falcon main. And I think that is huge in his tier placement.