Hi Phil,
not meaning to be rude, but this is why I am an accountant and you are a pilot (I assume).
You look at the technical aspects and say "this is the best aircraft"
I look at the financials and say "I'm an accountant, what's the answer you need to swinhg this one past the shareholders and get that huge bonus?"...
err sorry umm rather "what are the financial implications of a 250 seat aircraft against a 219 seat aircraft"
The financial implications (just on the fuel burn) are that with an extra 31 fare-generating seats the fuel penalty is not signifcant (within certain parameters).