I took it up to C Minor, or only 3 flats, and arranged it for concert band (obviously fixing the god awful singing into a suitable key and harmony). It made it sound suitably go-get-them. But that wasn't it.You can find both versions here. Many thanks, Dimondium!
I recently took it up another 2 semitones, to D Minor, and OH MY GOSH IT SUDDENLY SOUNDS SO FREAKIN' EPIC, as well as being EASIER—One flat in C. Enjoy! If a note must be made: if you like traditional keys, C Minor is your bet. If you like better sounding, but a bit different and situationally harder based on your band's training, D Minor is yours.
Cutie Mark Crusaders Into C Minor and D Minor
Dimondium shared two new versions of the Cutie Mark Crusaders theme—transposed into C Minor and D Minor. I'll let him explain (since you can't beat his enthusiasm):