This is a very good piano module, it sounds very nice even when using headphones. Have you ever listened to a 'piano' from a GM/GS/XG module using headphones? Well, try it and you won't like it...
However great it may seem, there seems to be a small problem when playing notes with strong velocity around the middle C - there is a faint scratch on the right channel. You can only hear this when using really good headphones, so I don't worry that much about it. I believe it's a design defect that even Yamaha hasn't bothered to confirm or deny (not that I've asked them), because I know at least two other units that behave the same.
This box won't leave my rig until I find something that's a lot better,
and I don't think that's going to happen in the next few years.