The titanium or ceramic heat shields as well as titanium pistons are used to prevent the boiling of the fluid in the caliper. I've never had a problem boiling the fluid with the 500E. I did experience this with my 87 300E. I solved that with brake cooling. The heat shields or ceramic backed pads will not improve braking performance - only help to prevent the fluid from boiling.

Brake cooling will improve brake performance, prevent fluid boiling, and especially pad and rotor life under extreme conditions. I don't believe that the heat shields really will offer any substantial benefit.

The best source for a definitive answer would be Alcon.