So a guy was playing a fighter 11/barbarian 3 (maybe f12/b2). He was sacrificing his highest attack to use Rapid Attack to move around and attacking and slaughtering. He used Wild Fighting to give him an extra attack at his highest level (-2 on all attacks), basically getting back the one he sacrificed to use rapid attack. Add in haste, he was doing 4 attacks (2 at his highest, though all at a -2 penalty) and being able to move in the same round.
My thought was that since he sacrificed his highest to use rapid attack, the bonus attacks due to wild fighting and haste should be at his second highest bonus, not his highest. Basically he was making his second highest attack his new highest attack bonus.
"Highest bonus" is shorthand for "Highest base attack bonus" in this case, and thus you'd use the value the barbarian derives from their first attack, not their second.
The ability specifically calls out that they forgo their highest attack, it does not change the fact that the bonus is their highest attack bonus.
So yes, the barbarian was doing it correctly.
Yes, the trade is one attack for movement, not all your attacks at the highest bonus for movement. He's being pretty smart about it, actually. Most Mobile Fighter's I've seen are dual-wielders...
Yeah, I figured he was doing it right, it just seemed a bit munchkinny to me. Basically the way he was doing it was he got to move and make a full attack by only taking a -2 to all attacks and -4 AC (he was just doing a shell game of using the barbarian ability to get around the fighter ability negative).