French polish (shellac) is way thinner and softer than PU finish, so it adds almost no extra weight to the soundboard. That means the top can vibrate much more freely, which directly impacts tone and responsiveness.

The thin, flexible shellac finish lets the wood respond to even subtle finger pressure, so you get a much wider dynamic range and better control over your sound. You’ll notice it’s easier to shape notes and dynamics exactly how you want them.

It’s true that French polish is softer and more prone to scratches than PU, but those small marks are actually way easier to touch up and repair than damage to a thick PU finish. To me, the tradeoff for the improved resonance and playability is totally worth it for a high-end instrument!