I haven't yet rewritten Into the Depths nor asked my dear pal Chris Huth to remake the one-page version, but I have been playtesting it a lot this year via my Feuerberg campaign. I've been collecting player feedback, and noting my own feelings about things, and here's what I'd change:
1) I'd increase saving throws to success on a 16+ instead of a 14+. This would make it harder to save, and make bonuses to your roll from gear and the like more important. It starts you off with a 25% chance of saving, instead of a 35% chance.
2) I'd pull the helping rules out into a separate section called "helping" since the "Turn your 1d6 roll into a 1d8 roll" rule seems to be the most commonly overlooked rule in the game, and its current placement under risky and dangerous actions make it appears like it only applies in those circumstances, as opposed to more generally..
3) Shift getting "Good Ats" to odd-numbered levels instead of even-numbered levels so that you get your bonuses spread more evenly across levels - improvements to your scores on even levels and Good Ats on odd ones. As it currently stands odd-numbered levels are comparatively dead, while all improvements happen on even levels.
4) I don't know that I'd use it in my online games where we tend to have more of a "pawn" style of play, but I'm strongly tempted to add a rule where when you camp, if you tell a unique story that relates to your character's backstory and describes them doing something interesting, you can become Good At that one thing for the rest of the adventure. Alternately, I might make this the effect of a boozy party item.
5) I should probably add some Bad At rules where you only roll a d4 instead of a d6, with each Bad At giving you another Good At.
Those are the main changes I've noticed and wanted to make, though if any readers out there have more, I'd be willing to take them under consideration.