I have 200 miles on it with a resistance of a cruiser in P- 0. However a grinding sound louder than a coffee bean grinder and very hard pedaling in any P assist levels. (Think of your car suddenly dragging it's muffler) .
It goes away when I use the brakes and will coast. The sound returns after a 1/2 pedal turn.
To early to tell, considering that Pace 500 have been manufactured for only a year so far.
Gears could last more than 10,000 miles but hall sensors and magnets often fail sooner. The word is that Shengyi geared hubs are inferior to Bafang hubs, but a lot depends on how you ride so it's difficult to compare.
"Sounds" like you got a lemon. 200 miles is way too low for even the cheapest no-name hub.