No idea on the PS420
Too new, no reviews, and haven't used one. The specs look good on paper but paper doesn't make chips.
That said, (for better or worse), see if you can track down a Dolmar PS401 at the dealer. He may still have some in stock. I've had the opportunity to run one and they are a nice little saw, perfect for your application. They are light, reasonably powered, and reliable.
The local Dolmar dealer that also carries Husky and Jonsered sells a bunch of 401's to homeowners looking for a decent small saw at a price point to compete with the big box bottom end Huskys. I tend to agree with him, the orange Poulans that Husky sells are not much of a saw. He doesn't carry the new Dolmars yet, waiting for feedback before he makes his customers beta testers. He did bring in a pretty good amount of 401's however.
Don't know if this helps or not.
Take Care