Balloonion attacks are dominant once you get L6 Balloons. I think you're correct, SP, that the Sweeper was established for exactly that reason. It remains to be seen whether it will be a real game changer.
SirSpank, give balloons a try again after you can make some L6's. I don't use Balloonion very often nowadays, but mainly because I'm only picking off TH's. When I drop cups and start facing more TH9's and 8's, I'll be using it a lot more....that is, if the 'puffers' haven't killed that startegy.