It's extremely hard to get the bonus for not hitting any gray blocks when playing as ninja mono on a really fast/intense song, because whenever you chain a bunch of blocks and they float off the board... they float INTO the traffic and you can't see where you're going thus hitting a gray block in the process. It's not challenging, it's extremely frustrating. I think that if you made the blocks maybe fade out from the position they're in on the board instead of flying forward blocking your view it would be so much better.
That's just my opinion though, I don't know if you guys intended for it to be that way but it's so annoying. D: