Epower is a great viable way to go for to 40 size and smaller. I have had a few and even learned to fly with them. But when you start getting in to BIG brushless motors with lipo cells for the 60/90 size your wallet needs to be loaded with cash to get the amps and duration a person would want. In a few more years i'll be switching to Epower again as technology should be safer and cheeper for my size of planes by then.