EC120, i don't agree with you. the temp gages especially the venom are very helpful tools. the backplate test may work for you, but what's warm for you is hot for others... if i would use your approach my os 50 would run at 320-350 degrees and that most certainly is not healthy.
no, engine temp is not the only thing you need to tune an engine properly, but it helps you monitor it, just like a voltage monitor... or you don't use those neither ?