Fwiw, I've got about 100k lifetime miles on AS and successfully had a VDB once, PDX-SEA in the early afternoon. $300 voucher and the gate agents rerouted me (at my request to swindle some extra miles from the deal) PDX-GEG-SEA. I got home barely 2 hours later than I otherwise would have.

I've come close a couple other times where the gate agent had me on standby waiting to see if the last few people would check in, and one other time when there were 2 seats needed so I got beat out by a pair travelling together who wanted it.