Only issue which I have puzzled about is at airports where OLCI produces a pile of pre-printed boarding cards awaiting collection at the airport (e.g. HKG and BDA).

At what stage do these get printed out and once printed does the prospect of someone having to retrieve the boarding card and replace it affect the chances of an op-up ?

Last (actually only recent) op-up was J to F in BDA where I was given a pre-printed J boarding card and told no op-ups although it was pretty obvious that the flight was probably oversold. I went and talked to someone in civies who looked as though she ran the show and she was happy to up me to F.

I got the sense that as the check-in agent had my boarding card pre-printed he was pleased to have no more work to do and did not give the request serious consideration. A downside of OLCI ?