I'm looking for a new chain saw. Echo CS 450, 490 and the 590 Timberwolf in mind. I'm thinking another 18" but I am open to a 20". I will use it to cut firewood and fallen trees on the property after a storm. It may get 4-6 hours a month. I just want a good saw. I don't want to have to toss this one after a few years. I'm thinking the 590 is the way to go. Thoughts.