Our trip back in Feb (as per illustration above) was delayed. The old queen had an engine sensor that stopped sensing. So, with all on board and doors closed - after nearly an hour, it was everyone off and into hotels. A full 24hour delay due to crew rest. As the flight was 99% (estimate) full, and we all had to be put up and fed AND all received the EU.261 (just over £500 each) it was a really costly delay.
But, as I have said, you always felt secure. It seemed to me that, if there had been a ground incident or some such, the machine would have been a good one to be in. From my point of view, I would choose a 20 year old 744 over a brand new 787 any day. And have done so!