The current way multipliers are balanced around are to make them work for the upcoming MWC. We are aware that giving multipliers to visual mods is a risky touch, especially due to lacking alternatives to compete against visually obstructing modiers in terms of map ranking. If we (ever) make this scoring to replace the current one, we will put efforts to rebalance multipliers around to make them work with other competing modifiers, of whichs difficulty increase is not based on altering the visual perception of the beatmap.
For now, it is working fine for the structure I am planning for the MWC and we will test this out and then make adjustments based on it.
Fwiw, I would ask everyone to mostly test the 20/80 ratio balance. We won't negate the meaning of combo entirely, but I am aware that basing the score solely on accuracy also is not serving the purpose as it should. I feel like right now, it pans out pretty solid, but if you are encountering situations, where the scores are not resulting the supposed rank placement, because the combo weights too much, too less, etcetc., just let us know and try to bring up a viable idea of how it actually should be, so we can adjust around that.