Well good morning sunshine!
your up early lol. We should get some good info and opinions over here. Looking forward to it. I'm not really sure about the efficiency deal as I don't have the equipment to test for it but I have noticed that the current will drop on higher voltage/lower kv setups. That is really the main reason I go that route. The setups quoted were a prime example. The 4.5 vs 6.5 setup runs about 40 degrees cooler on 3s to the 2s. Working in Merced right now and it's been raining so the outdoor tracks are too wet for me right now but when I can I will get some amperage data for comparisons sake. Thinking your right about the efficiency deal but on the other hand with lower currents there would be less heat losses so maybe it's a balancing act between the two? Awaiting mr g to chime in, sure he has some insight on the topic.