Well... I did say:
ignoring a whole bunch of variables, just looking at the "steady state" and using some slightly suspect numbers
To be absolutely honest my very first post was a bit naughty. It was just that the seat discrepancy (219 vs 250) was so extreme. (actually I thought that the 219 for the 787 was way too low)
Obviously basing my entire argument on just 2 sets of numbers (given mach & given seats) is pretty much like constructing a skyscraper on sand and without foundations.
But it still stands that a slightly less fuel efficient aircraft can be financially the better option if that ac has a higher revenue-generating potential.
(and that the demand exists and etc etc etc)