Hello, i would strongly recomend use this chain for det the setup om the 900E:
CN-E8000
This is Shimanos 11 speed e bike specific chain, the reason why i would use this is that Shimano has patent on there chains and chanrings. if you take your Shimano steps chainring and put the KMC chain on, take a flashlight i try to see if there is small gaps underneeth the chain and the sprocket. You would see the KMC chain propably wouldnt sit right on the chainring.
I do not know the strength difference other then that the KMC chain will wear out quicker becuase it do not fitt 100%. Also our e-8000 chain gears better becuase the outer plating on the chain is matched better with the gear ramps on the cassette.
Regarding of spec with other chains is just a money question.
As you may figured out i work for Shimano in Norway.
The World's largest electric mountain bike community.