As an ambitious photographer in the OM-D cameras does not come along well without spare batteries I recommend to look in your wallet and buy accordingly. Who can afford it, will always take the Originaakkus order to be on the safe side. The batteries are perfectly fine and work as expected.
Competitors such as Patona provide adequate performance for a lot less money and might be a viable alternative, especially since one buys about two equivalent products for the price of genuine batteries. So far, I could not tell the difference in performance between original and replica at my E-M1.