It doesnt matter how much wood you cut with them it's all about the size of the wood you cut. In little wood like you're cutting a 50cc saw is fine and just about as fast as a 70cc saw but if you get into 2 foot logs you're going to want the bigger saw. I use a 50cc saw most of the time as I cut up smallish wood most of the time.
Kinda does If you cut alot of wood and you get big round in that wood gonna want a big saw even if their is small stuff if you cut small wood you gonna want a small saw trust me I do this everyday go you dont really whant to cut each side with that small saw it isn't the fastest saws so for small and big stuff you want big saw so big bar = not bending over as much but do what you please
