Also, here's a little something you might appreciate to know about the 'approach speed' of mods
The value of the approach speed represents the rate at which the mod in-/decreases the application by 100% over 1 second.
So for example, '*1 Stealth' means that the notes will go from 0% Stealth to 100% Stealth in 1 second. If the player happens to have Stealth on already at a value between 0% and 100%, the tween will finish earlier than it would when the player has no Stealth at the moment of the mod execution. So if timing is important for your mod transitions, this is something to take into account.
This is especially important in case of speed mods. I only experimented with XMods so far, where a rate of *1 means that the speed mod will tween at a speed of 1x/sec.
So for example, if you want someone's notes to go from 1x to 2x in 0.5 seconds, you'd apply *2 2x'. But if you want it to go from 1x to 3x in 0.5 seconds, you'd need to apply '*4 3x' (because with *1 it takes one second for a diference of 1x, so a difference of 2x at twice the speed means *4).
Hope that wasn't too confusing of an explanation. Let's keep sharing our findings and knowledge