When the EM first came out, as a lower cost consumer body among rising prices for the other bodies, it caught flack for not being a real Nikon from some people. (I can hear the Monty Python guys, "It's a man's life in the Nikon army!") I remember a few with some electronics problems early on, but as far as I recall, that got cleared up. The E series lenses were also not as well built as the standard line, but at least some versions had reputations as real "sleepers", good optical quality and value for money if you didn't hammer and slam them around like a photojournalist.
Have fun with them, and don't let anyone tell you they don't hold film at the right distance behind some good lenses. If the electronics have lasted until now, you're probably not in great danger of sudden failure.
If you offered both, I'd take your Oly gear over the Nikon, but that's purely a personal preference.