This is really good work, and thank you for sharing the results.
This seems like a very practical approach, and one we should probably all be using. We'd get even more leverage by pooling our results, because it might help identify configurations that are especially low noise. There's a bit of gray zone though, because you're measuring the top of the noise floor rather than the bottom of the noise floor. That's where your earlier histogram (on another thread) adds a level of insight. So if, say, using a particular power source caused high interference 10% of the time, maybe you could still receive your packets from far away if one of the re-transmits happens during the other 90% of the time. Of course, to save power one wants to minimize the number of re-transmits needed, but the end result may not be quite so dire. Still, one can what-if and analyze things to death, and I think there's a lot to be said for keeping things simple so that everyone can use it. Your approach steers clear of the grey zone, which is what we should all be aiming to do anyway. So, bottom line: hip, hip, hooray!