I don't know which one is, but I know which one is not. I've had an 039 with a 20" bar for about 10 years now and it just always seemed like it wore me out to use it. I got a MS 460 with a 28" bar last fall, and I know full of fluids and with the longer bar and chain, it's somewhat heavier than the 039, but it sure as hell is a lot less tiring to use. If I'd have known then what I know now, I'd have bought a pro saw instead of the 039.