The penalty applying to an overweight plane does appear poorly worded when placed under scrutiny. It looks like the people that worded it knew exacly what they wanted it to mean, but I wasn't there and can only debate the written word.

At least with the noise rules it's fairly clear if the plane fails the test before AND after a flight then that particular flight is zeroed, not all previous flights or the plane/pilot disqualified for the rest of the comp.

Is running a noiser prop on an electric to extract more power/performance any less cheating than slipping in a larger pack for longer lasting grunt?

From reading the debates that pop up from time to time I think in most if not all countries handle this issue with maturity and common sense and if your plane conforms reasonably to the spirit of the rules than you're OK to compete, unless it's Nationally or Internationally significant comp.