Stubble got it right, if you take a unfluted barrel and then flute it, you might have weakened it. But you did increase surface area. Will it make any difference in cooling? According to one of my mechanical engieers here at work, it might cool 1 min faster to a X temp at 10 min. Big deal.

Where it counts is if you buy a 8lb barrel unfluted, and then buy a 8lb barrel fluted. Then it might be more rigid.

I am not a huge fan of them. One, its an extra crack to clean. Two, I like the smooth look of an unfluted barrel. Three, they charge a fortune to do the flutes on custom barrels. It I was building a super featherwieght, I would flute. Cause your whole purpose is to slice oz's off.