I think I am with Hot Water here. "Synchronous" can mean matched at any angle. The only time an articulated is "unsynchronized" is when the drivers slip.
I think you are all talking about engines being "out of phase". Since any angular disparity would be "locked in," I would say that having both engines in phase is just as likely as having them at, say, 30 degrees forever.
And indeed while I favor Mallets and articulateds, I find the amount of angst over this sound system a bit over the top. Is there nothing else wrong with this model? If so, then it is a winner!
I will not be buying one - last count around here was ten Challengers, but no sound.