Seems like a reasonable option. Do you really think that a +1 leadership on one ship in the Carnage squadron is better than a third re-roll, though?
I mean, let's say it's squadron of three devastations with Warmaster, CSM, and re-roll. Two Carnages and two Acherons either make one big squadron or two reasonable two-ship squadrons. If you play the former, the lord seems reasonable. If you play the latter, the re-roll seems better, since either of those squadrons can use it.