I just had a shoulder replaced, and am looking for a really easy to start - REALLY EASY - midsize chainsaw, which seems to mean Stihl Easy2Start, probably a 250. However I see mentions of Sachs having a similar system on the 420 - Happy Start? - but I cannot find a single description of what it is or how well it works or test of it. And no Sachs dealer nearby, of course. Anyone know anything about it?