Just want to add my US$0.02 here.
A few posts back there was a comment made regarding education and loggers. I'm an over-educated sort, couple degrees and a bunch of military schools, and I sure as hell stand up and listen when anybody with the Voice Of Experience is talking. Day I stop learning is the day I shrivel up and die. As a Forestry type, I'm somewhere between the production and the consumption ends of the industry, and have opportunity to speak with both. Folks who know their business can be found wherever business is done.
Regarding the perennial "New-Vs-Old" argument, I think it's a no-brainer that first-generation products will be less robust than later generations. I also think that any technology that makes the effort of work more productive is a good technology. So: for now, I will maintain my current fleet, and as I replace them over time, I will not shy away from newer designs out of ignorance of their performance.
Finally: Metals has said repeatedly that he suspects elevation is a factor in the poor performance of the M-Tronics in his region. Brand-bashing and other disruptions have led to this opinion's overshadowing. I am inclined to agree with him -- all other things being equal, elevation increase results in a decrease of available oxygen. It's reasonable to suggest that this would be a cause of poor performance in a machine as simple as a 2-stroke engine, regardless of what accouterments are bolted to it.