Not that it is remotely measurable, but I am of the opinion that amber things flashing amber are marginally more noticeable, thus making the car a tiddly bit safer.
I do realise I'm a fine one to talk as my Morgan does not have indicators in the first place. And it seems about 90% of road users have no idea what I mean when I signal left with the right hand.
The circle by the way is anticlockwise.
