the unfairness of it is not something taken from the logs, but rather, by looking at the system
precise effect: +2/4/6 to hit, for 1,2,3 points
invisible effect: guaranteed hit, for 1 point, AND unable to be attacked while invisible.
since right now, at very low levels, stat differences are small, I'd say you need about a +8 for a guaranteed hit, meaning invisible saves you 3 points, which can be put into damage to deal 3d4 more damage.
however if you take this lategame, if you want a guaranteed hit, you will need way more points into precise, while invisible stays a guaranteed hit no matter what. So you can spend WAY more points into damage, or basicaly ANY effect, making your attack simply, MUCH stronger than anything comparable.
and before you start argueing "but there are ways to counter invisibility", of course there are, but there are also ways to counter precise, so that point is moot. Thing is even high levels of the precise effect can be countered just by having unlucky dice, while invisible doesnt even involve a diceroll. If you want to counter invisible, you will have to actively work around it. And that either means bosses will have some sort of bullshit, madeup true sight artifact or some other nonsense, which is lame, or actively have to spend an action doing whatever it is they do to counter invisibility. That's an action they are not using to attack, to defend themselves, to debuff someone or anything, it's only an action to get rid of invisibility - which is a huge advantage for the one who went invisible, because he literaly stole the enemies action.
now, I am not saying that this shouldn't be a thing, going invisible is neat and all, and it really is not gamebreaking or overpowered. It's just not fair cost-wise. It's simply an effect that is way stronger than other effects, but costs the same as those effects. Anyone who thinks that a +2 to hit has the same value as a GUARANTEED hit AND avoiding a large variety of attacks at the same time should be equal in point-cost should at the same time be fine if you deal 1d4 damage for every point taken in damage, while someone else deals 5d4 damage for each point taken in damage.