Nobody posting experiences here because nobody is buying the fares. I just purchased a ticket today and avoided the BE fare, and paid $30 extra for the round trip. Pretty sure that MOST others are doing exactly the same thing. UA will have very little data to look at to assess BE, but what they WILL have is a successful implementation of a fare increase across the board.
Probably only a few days away from seeing BE (I will refer to it as the fare increase) hit flights with connections.