This might not be too relevant any longer as IST went for a price increase plus quotes xONE fares in Euros now but just wanted to add a new entry to the list of "positive BA IST xONE -experiences".

We picked up our USD priced DONEs that where ticketed in March yesterday from BA's airport counter, arrived there around 90mins before the flight and our machine printed 19 segment tickets where waiting for us right in front of the clerk, clearly pre-arranged, perfect work!

Highly recommended as an overall experience to deal with them and anyone who's trying to get tix by fedex, I would recommend to skip the hassle and just pick up from the Ba counter pre-flight.