I simply don't believe any of these sound characteristics are related to the grade of birch used after it's been glued and pressed to hell and back in a high pressure shell mold.Density/ Quality of Density/
Sound Character/ Sound Sustain and Drop off/
Cheap Birch and an Expensive Birch/
But you would certainly use the highest quality wood if you're spending the time and money to have top notch craftsmanship, finishing, and hardware. You're creating a premium product.