I know Condor (saddly now Thomas Cook in that ugly livery) flies them with great success. They also can turn them in less than an hour. LH was running test services with them FRA-MUC a couple years back, and seemed to do well. I think that a lot of this has to do with LH seemingly going all-Airbus since the 744 order. Except for the two leased stop-gap 763ERs, I believe their last 2 or 3 744s are due in the next couple of years, then it is all Airbus. I think the 753 would be a good fit because of the economics and the fact that Technik already has them in all the time with DE