After watching the 550 video over and over again, I'm even more blown away than I already was. I mean the rpm's in the wood that thing is turning is impressive to say the least.
I myself have had two modern 60cc saws, a 361 and a 362. Both were fine saw, however I no longer own either. With the 550 being what I think it is, the 10cc gap wasn't just closed in my mind, it was obliterated. Even if the 362 has a slight power advantage, {which I now question after watching the video a million times} we have a 10# 50cc saw with as much or more power than any 12-13# 60cc saw. I've been on the fence about the one saw question for some time, I now see no reason for a 60cc saw whatsoever. Now if the 562 I ran was truly a one off dog, and they really do run, I may change my mind.
Pertaining to the question of using a 50cc saw to cut anything 20" or larger, this is what I've found over the years. More often than not after felling a good size tree, I start out bumping the branches with a 346, and before I know it I've bucked up the whole tree without ever even stopping to look at one of the big boys. Lets be honest, most make do heating their homes with a lot less than a 70, 80 or 90cc saw, it's not realistic or logical for most to go out and buy a $1,000 saw to cut 5-10 cords of wood a year. This is where I think the 550 will kill the competition.
My .02
Andre.