For 100% shouldn't you need to get all Hint Coins as well? Or is just completing all 70 puzzles to get the Gold stamp all that's necessary?

For Layton Speedruns, 100% and All Puzzles are separate categories. 100% requires all Puzzles, all Hint Coins, and all collectibles (should the game have them). So yeah, it does!

Layton speedrun leaderboards operate in a "run first" mode so if anyone does a 100% run, I will add the category to the leaderboard.