I think the OLCI has had a big impact on the old system of booking, very soon I think every passenger will have to use it. Whilst people still just arrive at the airport and the ammount of people using OLCI increase the overlap must cause quite a few problems.

Basically OLCI can be used to re choose seats at the last minute and if someone has decided to double click on a seat thats not yet been confirmed then its gone.

I use OLCI now every time AND get there 3 hours early.