SawTroll
Information Collector
I'd still stand by what I said - pick what you like, not from the spec sheet. The differences are small enough that price and dealer are more relevant.
Until you look at 346/550/stihl 241 there isn't enough between these saws (stock) to get excited about.
As far as I know, the PS-420/421 comes with a spur sprocket and a plastic clutch cover - and Dolmar doesn't use 3 digit model numbers on pro saws.
Those saws also are a bit heavy for their power, but the very low US prices are of course attractive!