Is that really such a strong balance concern, though? I mean, almost all of a fighter's class abilities (the feats) are non-exclusive, meaning anyone else can take them. Shouldn't a fighter be able to at least exercise this non-exclusive class ability set better than other classes with whom he shares it? I don't really see the fighter being privileged over the ranger by having access to Diehard and Endurance as bonus feats; the ranger still gets Endurance for free, gets fighter-type feats (the Combat Style trees) for free, and has better saves and skills, class abilities, and spells.