Setting a fixed score multiplier for HR and EZ, with the current accuracy formula (accuracy percentage scaled with x^(1+4x)) makes it so there exists accuracy ranges that determine which mod is the most convenient (maximizes the score part of the total score) to use depending on the level of accuracy of the player.
The table is interpreted like in the following example:
If in a map a player gets in average 99.5% accuracy percentage with no mod, then he would get in average more accuracy score using HR if it's multiplier is x1.024 or more (if it is lower than that, then no mod would give in average more score), similarly, the player would get more score in average with EZ compared to No-Mod if the multiplier was x0.894 or more.
IMO, those ranges where in average players get more score by using a specific timing window mod shouldn't exist, the player should get the same score if he plays the notes the same way, regardless of the mod used (and make the mods just a change of scale of the worth of the judgments, analogous as being able to measure the mass of something with either kilograms or pounds). Since the accuracy part of the score only has information about the judgment counts (and not the exact timing of each hit), this is not possible in the edge case where the player gets 100% accuracy or close to it (but it can be accounted for correctly, by making rainbows different to 300s in the accuracy part, and considering the amount of notes to penalize based on the probability the accuracy obtained was far from the expected accuracy of a play; or even better, make the timing windows of rainbows constant regardless of OD and Mods).
Edit: Another possible idea:
Add a new judgment beyond Rainbows (300g), with a tight fixed timing window (for example, +/-10ms), which is required to hit for every note to get 100% of the possible score.
Advantages of the judgment:
The table is interpreted like in the following example:
If in a map a player gets in average 99.5% accuracy percentage with no mod, then he would get in average more accuracy score using HR if it's multiplier is x1.024 or more (if it is lower than that, then no mod would give in average more score), similarly, the player would get more score in average with EZ compared to No-Mod if the multiplier was x0.894 or more.
IMO, those ranges where in average players get more score by using a specific timing window mod shouldn't exist, the player should get the same score if he plays the notes the same way, regardless of the mod used (and make the mods just a change of scale of the worth of the judgments, analogous as being able to measure the mass of something with either kilograms or pounds). Since the accuracy part of the score only has information about the judgment counts (and not the exact timing of each hit), this is not possible in the edge case where the player gets 100% accuracy or close to it (but it can be accounted for correctly, by making rainbows different to 300s in the accuracy part, and considering the amount of notes to penalize based on the probability the accuracy obtained was far from the expected accuracy of a play; or even better, make the timing windows of rainbows constant regardless of OD and Mods).
Edit: Another possible idea:
Add a new judgment beyond Rainbows (300g), with a tight fixed timing window (for example, +/-10ms), which is required to hit for every note to get 100% of the possible score.
Advantages of the judgment:
- Scores that were close to the maximum score possible in the previous system would be farther away from it. Since they are farther away, the difference between the median accuracy and the mean accuracy of a player that repeats the map becomes smaller, making it not as necessary to compensate for map length to make a system that balances between different timing window mods fairly. This is specially important for easy charts, where scores of 1 million or very close to it are common.
- Even if there are scores that end up being close to 100% anyways, having the timing windows of the tightest timing window the same regardless of mods makes the differences between mods smaller for the high accuracy range (virtually the same for 100% and close to it), so there wouldn't be need to compensate for map length even in that case.