That is a pretty good idea. Adding 1d6 (or the best of 2d6 or then 3d6) was just another bonus in 3rd edition. In 5e, being able to roll even 25 can be an issue.

That being said, other dice such as bardic inspiration or cleric spells add dice.
My issues, is the action point dice can make these other resources less

I’m going to have a pretty good idea once I complete my current campaign.

Unlike advantage, I would not consider the additional die for crits, so a 17+6 is a non-critical 20.

That’s certainly true but on the other hand Advantage/Disadvantage can end up being decidedly underwhelming too, whereas a die adder actually maintains some excitement of being able to achieve the impossible.

WotC screwed up some of the bounded accuracy math, though. Very high DC saves are a good example. By about 9th level it becomes essentially impossible for a proficient save character whose prime requisite lines up with the proficiency (e.g., Cleric and Wisdom saves) to fail all but the absolutely hardest saves. Vice versa even high level characters where proficiency and stat don’t line up (e.g., Fighter and Wisdom saves) are essentially locked and Advantage is no help without a die adder. There are some other examples but saves are the most important ones.

Good points. I think the d6 has greater potential to “break” bounded accuracy, with lower level (especially bards, rogues) to get rolls in the high 20s or even low 30s.

Finally, I’d like it to be able to do other things than just Advantage, which is often pretty underwhelming. Some other choices would be nice: Gaining a number of temporary hit points or a turn free of persistent conditions both seem apropos.

And it really must be said: Bad WotC, naming something like that the same thing a class-specific mechanic!

The benefit (cost) of advantage (disadvantage) is a bit more complicated. It depends on the number you need to roll. The closer to 11 you are, the more beneficial. The bonus there is more like +5, and it tapers down linearly to either side. Advantage is of little benefit for high numbers needed to roll. It also not quite doubles the chance of getting a critical. By contrast a static add of +D6 always has the same effect regardless of the number needed to roll. Also, unlike advantage you can exceed your natural ability with a bonus die like +D6. They’re really not the same thing.

Over the past few years we’ve played several games with some sort of “bonus resource” such as fate points in Fate, Momentum in Conan, or XP in Numenera. My players love having something like that to gain an advantage or to avoid a disadvantage.

We also use Inspiration to make “story declarations” on occasion. I have even used Inspiration in the same manner as a GM Intrusion in the Cypher System.

That is a really great table rule. rewards players who continue to play to their background, without allowing them to bank for next session. Even if you could only have one token, having inspiration disappear at the end of the session would really create a use them or lose them mentality.

The only modification we’ve made to inspiration at our table is that you can bank multiple “points” of it but you lose all inspiration at the end of every session. This has worked out great for us!

One of the games I play in is using a hero point variant where you get one every “chapter,” and you can refresh it by doing something cool (normal Inspiration stuff) or by rolling a natural 20 when you using the hero point. You lose the die for the chapter if you roll a 1 on the die, unless you do two cool/risky things that would result in Inspiration.

In this case, it’s taking a lot of GM guidance to continually remind us all we have it, etc.

I am always a fan of more options that work for different groups, for sure.