Ok, I'm getting ready to book my trip. Thank you all for the help ^
I'm sure someone has started their xONEx in Finland? Where did you book your itinerary? Because I just called Finnair Contact Center and also Business reservations and they mostly panicked when I started to talk about OneWorld Explorer ticket

Big help they are, couldn't even tell me the base fare of the ticket. Maybe I should use BA? Would that work better?