I've never seen a Echo on a logging site. Never seen a Jonsered either, but the local dealer sold a fair amount. In this era I am talking about they were red Huskys.Yup, there's a fantasy land somewhere where Echo is in the hands of professionals. At least echo themselves are realistic.
In over 35 years of working with hundreds (yes, hundreds) of sawhands I never saw an echo. Husky, Stihl, Jonsered, an occasional Dolmar. In that order.
I have a 590. It's a "farm saw", and the first one I would sell. Even before my china saws.
That being said, I might like a 501p. It feels good in the hands. Light and nimble I think. I've only held one. Haven't run one.