The real control and care is to watch the heat -- nothin else really matters -
I now am running my Rotos over 9000 - onthe ground and my new 50 NG ZDZ at 7400 -
If you think about it - this is really not "loading" the engines in most cases
I used to run my gearbox OS .61's at over 15000 on the ground - no problems - but if you really load on the prop - and heat em up -you can ruin the whole shebang.