Question regarding shimano 9/10 speed compatibility. Looking to upgrade front derailleur from 105 (2003 variety) to either ultegra/dura ace. However, the current 105 FD is matched with a 9spd drivetrain, whereas the new ultegra/DA stuff is clearly 10 spd. Will a new 10 spd FD work with a 9 spd drivetrain, or am I forced to find a 9 spd FD? Clearly the 10 spd chain is thinner than a 9 spd, but does that mean that the derailleurs are too narrow for a 9 spd chain?