Just picked up an Echo CS-4010 to replace a CS-310 that wouldn't stop leaking oil. My dealer didn't want to sell it because they had some old ones but I told them I would buy this new one and not the old one. I got it home an oh man is this thing amazing. So much power, perfect balance and so light. It's 0.6lbs heavier than my CS-310 but it has about 45% more power and an 18 inch bar which my old one was a 14 inch. This thing is way better than I expected for the weight and price. It's a new model replacing the CS-400. I'm hoping this one lasts a long time. This is my 3rd chainsaw in 10 years