It's easy enough to thin out a rich piano into something thinner, an altogether different thing to make a thin piano rich...

Yes, the Yamaha pianos work very well in a mix, but play solo piano on them, they start to show their weaknesses. Better to have a solid solo piano and cut the mids with EQ, that to not have a great solo piano in it at all.

IMO, etc., etc.!
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An arranger is just a tool. What matters is what you build with it..!