British Airways.. flexibility when purchasing a ticket

While pricing out an airline ticket for British airways I came across the flexibility option which cost an extra sizable amount of money ($168.). I know I can change my ticket for an extra 250$ plus any difference in fare. Has anyone ever purchased this option with them? I'm wondering if its worth it to purchase this option as i may need to come home early or a bit later. Im hoping that the 168$ extra charge will be all that i would have to pay.?.im a bit confuddled! thanks in advance.

You would probably need to call BA and ask them to get a proper & accurate answer. Most of us would just be speculating.