CAP56,
I repeat my previous statement : "one does not T/O from an intersection on an 8 hr flight"
that statements displays a shocking misunderstanding of how flex takeoff and runway data is used, and how much extra runway your really have.
Assuming that the pilots took off from the intersection and performed a flex takeoff with the right numbers for that intersection (and that the flex cap would not have been reached on full length), performance wise there is virtually no difference between taking off from an intersection and full length as long as appropriate flex numbers are used. Infact, once airborne, your climb and engine out performance would be better having gone from the intersection (though full power is always available, it is not figured into an engine failure scenario)
If your statement was "One does not flex ( or reduce thrust) on an 8 hour flight" then you might be improving safety for your leg of the flight (though probably reducing it somewhat for the next chap who flies your plane as you put more heat into the turbine, and driving up costs significantly for your airline) But a flex takeoff from an intersection or full length has pretty much the same margin for error. (again assuming that a flex cap wouldn;t have been reached on one takeoff instead of the other)
Flex thrust trades thrust for runway length effectively making the whole available runway required. Use a somewhat shorter runway length and more thrust is used. Use a longer runway and less thrust is used, but effectively froma pilots point of view, flex power is making every takeoff a maximum performance takeoff where a delayed rotation or abort after V1 will send you off the far end of the runway.
Cheers
Wino