I have almsot the same point of view than kriers to be honest about MOST of the high bpm players who don't know how to play low bpm.
But about playing high bpm from low bpm i don't think it's hard at all, i started playing normal then went to hard and sticked with hard and semi insanes for a looong time then slowly started playing hard insane and another's .. and i improoved my bpm without loosing the accuracy on slow ones, which i think can be done easily unless you're a mouse only player (which it's already known has a cap on streaming speed), and that's pretty much all i think.
But about playing high bpm from low bpm i don't think it's hard at all, i started playing normal then went to hard and sticked with hard and semi insanes for a looong time then slowly started playing hard insane and another's .. and i improoved my bpm without loosing the accuracy on slow ones, which i think can be done easily unless you're a mouse only player (which it's already known has a cap on streaming speed), and that's pretty much all i think.