RE: Don't understand
Size and weight can be a problem. There's a heckuva difference between a 4c 700 NiMh pack (AAA cells) and a 5c 2700 NiCd pack (C cells). With a big plane I agree, but I had fits in one of my planes (Modeltech Magic Extra) trying to squeeze a 600 4c NiCd in. Other planes just can't tolerate the several ounce difference in weight, or at least the placement of a heavy battery such as that. All things being equal, I agree, bigger is better, 5c's better than 4c.