ive heard the same rumor of amber coloured bands too..not sure if its true, people also add a fancy name "surgical rubber"

...makes it look more professional...
cant say i have felt a diffference between black and amber and blue for that matter

Rob allen and rabitech i think produce some of the best bands..when i say best its based on the perception that they retain their elastic qualities, not too tough to load, retain power and dont wear out easily...
having said that i also find bands by seatec and picasso to be very nice..as well as omer...i didnt like demka tooooo stiff..