I just wonder if the market segment that buys Yamaha e-series and/or Casio are all that discerning about sounds. I suspect it's more about low price and availability. Obviously the segment is large enough and you see more Yamaha about than you see Casio, around here anyway. But if someone is looking for a decent keyboard so that their eight year old might get interested, then either one is a decent choice, and many a parent won't look any further than what's in front of them in the store.