ah!~ This is wonderful. Your harmonic choices are very nice! I'm biased for piano so Its not a deal breaker for me personally. But if you want something with a bit more balance, id really look at ORAS's Ending theme. In that track the piano maintains three core elements, (Rythm,Harmony,Melody) However it will reduce its prominence in at least one of those areas to spot light one or more of the other instruments.