funkysawmans got a good point
my cousin bought a 570, it didn't have alot of umphf to it, it wasn't real torquey and didn't seem to turn many rpms, I know even with that saw though I would want two good falling dogs on it, if You know the saw and how it operates You can usually keep it from dogging down on You, not to be rude but if you don't know the benefit of two good dogs you might just want to stay with what came on it till your'e a little more seasoned.