Battle High is fine as it is imo. It is true that the bh team can snowball, but there is a 2nd thing in factor that balance bh buff, a thing that basically in every bh forum post I read I never saw mentioned: limit break charge time.
If a team has lot of high bh players, they are probably the winning team, thus their lb charge slower (x0,75); meanwhile the 3rd team lb charge faster (x1,25). And if you can use more lb during a match, you can deal more dmg.
The difference is pretty big: 3rd team can use 66% more lb than the 1st team, giving a way to the losing teams to fight against the bh team.
Let's make an example: dragoon. Drg lb takes 132 secs to charge if you're winning, but only 79 secs if you're the 3rd team. If the match is let's say 16 minutes, a drg that is winning can use its lb only 7 times, while a drg in the 3rd team can use its lb 12 times.