Idk if Ace really has a better growth rate than Luffy. The gap in strength between Ace when he fought Jinbe and MF Ace didn't seem that wide, and look at the gap in strength between pre-TS and post-TS Luffy. Even though Ace wouldn't have been training as much as TS Luffy, he was still being trained by WB and growing in strength from fighting WB's enemies in the NW. So if Ace really has a better growth rate than Luffy, then I don't see how it's possible that Ace was only as strong as he was after that 3 year period. Also, I don't agree with using kid ASL's strength ranking to say that's how it will be/would have been. Using that logic, Ace would have been stronger than pre-TS Sabo, and I just don't see that being true since Ace was only the 5th strongest WB Pirate while Sabo was already the RA Second-in-command. And that logic would also mean that Sabo should be stronger than Luffy by EOS, which obviously won't happen.