I didn't notice a difference n/a while running a colder plug.
I DID notice a drop off in performance, however, when I gapped down the plug from the stock .045 to .035 when I decided to run the 150 shot. I definitely felt a decrease in power n/a when I did that.
If your running the 75 to the 100 shot, run a colder plug, but keep the plug gap the same, you will be fine.