Just wondering, that's all........
Increased fuel uplift would seem to make it even less likely that a 777 would file for an initial cruise FL of 450. Someone on another forum suggested a weight permitted final level of 410 at the tail end of a long flight depending on temps. I simply wouldn't know. Anyway I've just checked the biography of two of the journalists filing these sort of statements, and I suspect they were spicing up the numbers for effect or merely guessing, knowing their sub editors were not likely to spot 'oblate spheroids' or poor quality fiction. Last time I was much over 40000ft in a big aeroplane, it was very light and ceiling limited due to cabin altitude and something like electronic stuff altitude guarantee guidelines. There was a theoretical 1.2g protection in smooth air, and not too much gap between high and low speed buffet........not one of your new wide-bodies with super-critical wing and 777 level of technology though. I did one jump seat ride in a 777, but apart from the fact that it was over water and had only two engines didn't take much notice.
Funny how quoted experts so often aren't as expert as the bloke in the pub......