derek, any power ratings you find outside the US won't be relevant here. Due to EPA regulations, US saws tend to have a different muffler and/or carb tune.
That only lessens the power here in the USA if that is true. And 4.4HP out of a 68cc saw is nothing to brag about.
There is no doubt that the echo is a good, solid, and reliable saw. And it should provide you with years of service if that is what you are looking for.
But if you are looking for the fastest cutting (and still reliable) saw for $600 ballpark, the echo certainly isnt it.
To answer the question about the 570, NO it is NOT a homeowner saw. It is much closer to a pro saw than a homeowner. Husky likes to call it a "landowner" grade. But it is built like a pro saw, just a little heavier and somewhat de-tuned. The dont have as agressive porting and cylinder design. Thus the lower power and NON XP markings.
I have never ran them side by side, but the 570 is a good saw. And if HP #'s are accurate, the 570 should be a good bit faster than the 680.
Considering The dolmar 6400, Husky 570, and Echo 680 are all within a few bucks of each other, similar size and weight, Those are the three I would personally look at if I were in your shoes. Sure, the 372XP or 7900 dolmar are going to be faster, but @ ~$200 more money too.
Those three saws are close. I There is no noticable difference in speed between the 6400 and 570. I imagine the echo is nipping on the heals too. It all comes down to what YOU like the best. As far as how the saw feels in your hands. They are all good quality:thumbsup: