I think your leaving out a few things , good batterys need to be balanced and when stored for the winter stored in full charge and ideally at controlled conditions , in addition they can drain and need to be charged at leaste once per month at leaste this is what the e-flight guys tell me at our field . THen you have the life span of the battery , and ensuring that you test power (just like breaking in a 4 stroke) that you have a full charge and your getting max power . In addition I have seen guys try to save money on batterys only to spend twice as much the second time because the economy batterys dont hold up or provide the power as stated in the ads .
Now again , personally I have nothing against e-flight either and if you look at the CMP P40 conversion and the recent SKYSHARK p40 both posted on RCU , its makes e-flight look very very attractive . My problem is I think its still about 5 years away from -my goal =less weight more power for warbirds . I hate adding any weight at all to a warbird you will see that in every post I ever reply to on RCU . I dont care what the experts say (experts are people no longer willing to learn ) a lighter warbird flys better , and a weekend at the field with a better flying warbird is all I am looking for .