An interesting point that. When the new motor arrived, I re-used the chain, chain wheel and motor sprocket from the old set-up (many thousands of miles). The chain snapped after about 30 miles. I have now replaced the chain, rear sprocket and motor sprocket with new so I shall monitor the situation, but I'm not using the e-bike much these days, so it may take a while.
The 2011 Panasonic motor is noticeably more powerful than the 2008 version and this could be the problem. It delivers a lot of power all the way to 15 mph, with no gradual reduction like the old motor.
I haven't measured them, but I think that the motor sprocket and the rear sprocket are made from thinner material than the earlier versions that I had, more suited to thinner chain, which is strange.
I don't like the new motor as much as the old 2008 version. The new model climbs hills faster and gives a stronger push (in a less refined way), but somehow I feel cheated out of the, "cycling experience" by it. The old Panasonic was cycling, the new is closer to moped.
Ideally these newer more powerful e-bikes should have a more robust drive train. 1/8" chain, meaty sprockets manufactured from good quality material and probably a bespoke e-bike gearbox. Forget the 11 speed hub gears and zillion speed derailleurs, they simply are not required on an e-bike. 4 or 5 tough gears giving a wide ratio range built into a hub unit would make much more sense. The power of the new motors makes it un-necessary to have small ratio steps between each gear.