During the quest Come Fly With Me leader Jason Bright states
"Please, wanderer, bear in mind that every feral ghoul you spare now
is one that we can save later."
Is there any benefit to avoid killing the feral ghouls wandering the Repconn test site before or during the quest?
I've read Jason and his Bright Brotherhood will become hostile if you kill a feral ghoul within his line of sight; but that's only possible during the thirty seconds where he transitions from the upstairs laboratory to the basement launch pad.
If I complete the quest by sneaking past every feral ghoul do I earn bonus reputation, karma, experience, caps or even a line of dialog?
Best Answer
It looks like there is no direct benefit to sparing the ghouls in this quest. After replaying the quest using stealth and a pacifist approach there was no comment on or reward for the preservation of the feral ghouls.
As remarked in the comments it is possible to earn an extra 200XP for saving Harland and nonviolently removing the nightkin from the basement. Such a bonus does not seem to exist for ignoring the feral ghouls.
Notably, after completing the rocket launch the feral ghouls that are inside the Repconn Test Site are gone, taken on the Bright's Great Journey. This is also recorded in Come Fly With Me's wikia page:
The only benefit to be gained from sparing the feral ghouls is the conservation of ammunition and medical supplies that would normally be consumed while fighting them.