As somebody who's put over 100 hours into the engineer class, I've always been underwhelmed by the effect of the buff kit on the balloon. It takes a long time to buff, it runs out quickly, and a similar effect can be reached much more easily by using hydrogen. There's simply no point in buffing the balloon when you could be doing something more productive instead. And then there's an achievement for buffing 150 of them. This is pointless.
So I think that the buff should be changed to make it useful. Maybe have the buffing time shortened, the effect time lengthened, or something else. As it stands, there is no good reason to buff a balloon.