the bonus for stealth is practically 55% anyway - how hard is it to finish clean when you've got stealth?
And it's way harder to get clean if you're playing pointman and there's no stealth equivalent (unless you count the 10% possible from getting 95% of red AND yellows)
I think it's pretty balanced - just man up a bit and play with more colours.
Harder things should get higher scores.
'Harder' has nothing to do with it, its all about flow.
Flow is basically a zone where skill level matches difficulty and is what makes a game fun. If these two things are not in balance it is not possible to achieve flow.
When i play mono, i find it very easy to achieve 'flow'. That is, if i play a hard song, I can raise my skill to compensate and enjoy the game just as much as if i was playing a slower, easier song.
In any other mode however, i simply cannot achieve flow. Even on the learner characters, there is never a point where the difficulty of the task matches my ability. I simply do not understand what the point is, or what you are supposed to do.
Essentially what im describing here is the learning curve. I was able to learn and understand the mono characters with relative ease. I still fail to comprehend the pointman characters however. This is not my own stupidity, this is a design flaw.