That system would ruin a lot of multi competition between people of moderately different skill levels - it's pretty common for the better player to use HR or HDHR as a handicap and this would pretty much completely prevent that. Not sure about the rest of the idea, would have to think about it a bit more. At first glance it's not bad for people using the same mods (and pretty much how the scoring system in taiko works, iirc), but if this is meant to be specifically for direct competition, I feel like there's probably something a bit better that can be worked out. Or maybe not. Will think more about this later.