Ryan,
Your thoughts on hour meters aren't quite correct. Electrical hour meters (like you use on simple things like GTs) do not register hours with respect to engine RPM....they don't even care if the engine is RUNNING. The are a simple clock wired into the ignition circuit...switch on, it counts hours. Leave the switch on over night and your hour meter shows 12 more hours (that the engine didn't run).
Big tractor hour meters don't measure hours with respect to RPM either, some have curcuitry that assures that the engine is actually running, but otherwise 1 hour = 1 hour.
(think of the low RPM high load situation vs. the high RPM no load situation....which tractor would you buy, and would you want the hour meter "biased"????)