http://www.lucchicremona.com/EN/tester_tester2.htm

 in this link from the "deflection testing" thread it is stated that ebony ( paraphrasing here)  does not resonate well ( or as well as spruce)therefor it would not be a good choice for a violin body .

so.. then ... why have so many guitar builders had such good luck using ebony for their bridges???????   Jody