Your post, and reply to your friend intrigued me to do a little research myself. Reading up on the development of watch movements, in particular the use of silicon was very interesting and informative. Although I could not really identify who the other watchmaker was (would be great, if you could mention at some point in time, although Breguet did experiment early on with glass balance springs), the latest article I came across concerning silicon mentioned that Ludwig Oechslin was the Curator of the International Watch Museum when a gentleman by the name of Philippe Pellaton of the restoration department tested 25 silicon balance springs (UNITAS 6445, 18½, 18'000 A/h, lift-angle 49, for those interested) with Mr. Oechslin's report noting that "the results are sufficiently eloquent to insist on a larger sample." The rest is history.