I just picked up a dolmar 6400 for felling and bucking. I've been using a dolmar 510(50cc) for the past 6 years and it's worked great for everything but I wanted a second saw to bring out to the woods . I was looking at the 6100 to help buck the trees faster but my dealer steered me to the 6400(64cc). It was a pound heavier than the 6100 but it's very well balanced for bucking where it strangely feels very light when pivoting through logs and just rips through logs fast so much faster than the 510. It makes for a more productive day in the woods when I have two saws with me.