I have successfully changed a BE ticket to a main cabin and routing change outside the 24 hour window. I would not count on it but it doesnt hurt to ask. You may find the right person in the right mood, but also be aware that the person on the other end still needs to get a manager involved to do so, so they could also be overridden by that manager. At least this was my experience. I also had 5 other trips booked, GM, and was switching from a round trip to a multi city. By the time they changed it for me(cancelled and credited the BE and applied that to my multicity) it was about an hour on the phone and $50 fare difference.