G&L will be offering the saddles and block from the DFS ...

I wonder if it makes much of a difference in noticeable sound whether the block is zinc, brass, or steel? A technician told me they make them out of zinc alloy so that they sound a certain way and that changing the block could produce a brighter or duller sound that you might not like as much as the original one.

A good inch of the string is being pulled against the block, so sustain would be the biggest change. I'm pretty sure it's just a cost saving maneuver (similar to strats being changed from ash to alder back when alder was more readily available in the 50's).