Does this mean there's going to be a trend toward "low mass" bridges? 
I can see it now in the marketing campaigns ... soon everybody will know that low bridge mass means "more sustain"...
because literally everything you can possibly buy to do to a guitar gives you "more sustain"
And somehow this will be true of low mass bridges and high mass bridges at the same time!
Marketing.
Or as Yogurt (Mel Brooks) said in Spaceballs, "Moichandising."
The worst example I can think of in bridges was the claim by Quan that the Badass Bridge was made of special "tone transfer metal."
It was just zinc alloy.
Here's what I learned from Micah Wickersham at Alembic: the higher the mass of the bridge, the more energy is retained in the strings, and the less energy is transmitted into the body. That's why Alembic deliberately makes their bridges high mass, with a brass plate buried in the body, to have more sustain and to minimize the effect of the body wood on the tone.
By the same reasoning, lighter bridges transmit more string energy into the body. But you have to consider that different bridge designs have an effect too.
