With a properly adjusted mixture and well designed airflow, I know that even a pusher design gasser can run effectively and efficienly at temperatures of 120c and below. At mid range throttle settings that same engine can easily run as low as 85c. I also know that you're in trouble with eventual failure due to heat induced issues when you break 180c. 150c is a very good place to stop an engine and let it cool with a single, with 170c being about my personal max for a twin.

With the proper mixture and oil ratios (50-1) there's no reason that the plug will not last 50-100 running hours, even at the lower temperatures. There's far to much proof of that.

Pe, you market the engines that developed those numbers and I'm betting that you're aware of how much hotter us modelers are running engines that we should be.