Some things are inherently more dangerous than others. Chainsaws are kind of at the top of that list. Some have never held or used a chainsaw in their life.
I don't cut wood for a living. Never have, although my father's family had lots of relatives working in the timber industry. I'm a weekend hack, and do even less cutting as I get older. I no longer volunteer to help others cut wood like I used to.
Anyways, cutting wood will tire you. That's a fact. I never understood those that were concerned how fast a saw could cut cookies. What's a second or two quicker overall during a full day of cutting? You save maybe what, 30 min. tops?
If you are cutting and feel tired, STOP and take a break. I'm talking about weekend hacks like me. What's the rush? If you are a commercial cutter, then that's a whole other different story.
I have two saws. I feel I have whatever would be needed, for what I do. As I stated previously, weight isn't a big deal for me. No one makes a saw that is so light, it simply out classes all the other saws in it's category.
I can't imagine a lb. or two less weight would make any difference in my cutting. People need to take more breaks while cutting, not less!