Osage orange is ready to burn in 60 days in Kansas. It only has 400 lbs of water per cord green compared to when it's seasoned. It also doesn't absorb water at all.
If your looking for a lighter saw the 3510 is almost 2lbs lighter than a 400. I picked up a 3510 for $50 this summer but haven't cut any wood yet. It feels a lot lighter than a 400. My favorite small echo is the 2511p but it's $400-450.