That is preference, so don't worry about it.
I don't know any "insane" players in the osu!mania community that use up scroll, but I believe some are out there. I do remember one person trying it after playing down scroll for so long. They got bored of the game, and somehow, up scroll brought back the fun.
But there is one player that does play up scroll, and that would be Etienne. They are an Etterna player, but that shouldn't matter. You can do the comparisons yourself to determine the skill that he has.
I'd say stick to up scroll if you really want to, and don't change it if you feel like you are performing worse out of it. You're not. But I will see that it can be worth trying it out, to see if you like it.