Price matters to me as well - and there are other less expensive saws I would buy before a 421. I would buy a PP5020 before I'd shell out for a 421, and even if I didn't port it I have no doubt I'd have it running well because there's simply nothing wrong with the design.
It's important to keep in mind that the PP5020 you bought was a used/reconditioned saw that apparently had something wrong with it. And then you experimented with tuning on it - and we still don't know what's wrong with it (it might be minor). Most of what you're experiencing with the 421 is a saw that isn't defective and has been properly tuned. But it doesn't have any magic secret sauce that will keep it tuned any more that the 5020 did, as it has a similar fuel system. The case material and split case vs. clamshell makes no difference at all in terms of how a stock (or nearly stock) saw will perform or last for this use.
The other thing you and other converts to the 421 are experiencing is that by golly a good 40cc saw with sharp lo pro chain will actually cut a lot of wood. I have 8 saws from 38cc to 42cc, some stock and some ported, some plastic cased Poulan clamshells and some Zenoah split cased designs, and every one will do that too.
I agree with some of what you said and disagree with other parts but I say all of this in the spirit of civil discourse and hope not to give any offense as I do not mean to.
There's no doubt
you could get
anything running. There is much doubt that I or Joe Homeowner could nor if it was worth the time to do so when on a limited time budget. I can make any AR15 run well. I can diagnose what's wrong from barrel crown to buffer weight to extractor spring to gas port and beyond. That doesn't mean I recommend a cheap AR15 because
I can make any AR15 run. I recommend something that is problem free out of the gate or at least supported by a manufacturer that
will step up and fix the problem.
In my case, Poulan referred me to my local authorized repair center which was my Stihl dealer who was dealing with their spring backlog from the numerous arborists out here and they also advised that it's extremely difficult dealing with Poulan once the saw is diagnosed (diagnosis is the first step, no work can be done until the local authorized repair center diagnoses the saw and Poulan authorizes or refuses repair
and sends the parts). So, I do understand that under the hood the saw are essentially the same but you sure don't hear a lot about Dolmar problems as opposed to Poulans. Obviously, that's probably due to the number of each on the market mainly but I sincerely doubt that the same care and attention to detail is taken with a Poulan's assembly as is a Dolmar's. Also, in my limited experience and as reported by many others, the Dolmar 42CC feels at least as strong as most 50CC saws, mine feels way stronger than my old Poulan 5020AV even when I was running my 5020AV with a 16" bar.
If I have a problem with this saw, Dolmar or fordf150 will make it right. I absolutely acknowledge that I probably had a bad Poulan. I also happily admit that there's probably no way of statistically proving my hunch that Dolmars are assembled to a higher level of quality control than Poulans. However, I think that the Dolmar is a safer bet than Poulan for those that don't tear down carbs and redesign saws in their spare time