A little if any. The major difference is brake fade due to heat. If you brake hard and often, the gold pads sustain stronger grip in race-like conditions. As the previous poster mentioned, downhill mountain riding will benefit from the gold upgrade.

 

from the Lyndall site.

" If you are running stock tires, stock chassis and your bike is set up for stock horsepower then you should use the Z Plus pads, as they will provide as much stopping torque as the stock tires and suspension can effectively manage. The Z Plus pads will provide a noticeable upgrade to the stopping power over the stock pads.

If you are running aftermarket tires, high performance engine, have tuned your chassis (i.e. Gold emulator valves, upgrade shocks, etc.), or ride with a lot of gear or passengers on your bike, we recommend the Gold Plus compound as it is better designed to provide the most stopping power under any riding conditions.

If you are using our Metal Matrix Composite (MMC) Rotors then we recommend our Red Plus pads as they are designed to provide the most stopping power and longest service life of any other known organic pad. Our Gold Plus will also work with the MMC Rotors."

 

Yup, the reason I mentioned the difference in the mountains is this...
With dual-disk up front you are saved from a very bad squeal when you come down.
Stopping power is noticeably the same but the heat related vibration is much much less.