My grand father use to say "There's two ways to learn things, the easy way & the hard way. Unfortunately we learn the most the hard way."You'll loose any warranty BCM has on the barrel, and in my experience, shortened barrels often don't shoot as well as ones from the factory.
Is the barrel chrome lined? If they cut it and re drill the gas port, the chrome will start chipping away.
Myself I like to say "Don't ask my opinion if your mind is already made up".