I think it's legal, but I think it violates the intended spirit, and I wouldn't allow it in one of my games without a lot of thought beforehand.
My reasoning for thinking it violates the intended spirit is that it approaches the 3.0 Haste level of "You're either foolish or reaching hard for some other build if you don't take this"-dom.
I think most fighters would benefit from Power Attack, but they don't all absolutely need it -- maybe they're duelists who go with Expertise or fast guys who are gunning for Spring Attack or specialists taking the Focus/Specialization/Improved Critical path.
But the only monk for whom Improved Natural Attack isn't a no-brainer as soon as the monk qualifies for it is a monk who isn't focused on melee combat of any kind -- which is an awfully big reach for a monk.
Hence my "Maybe". It seems like a clear-cut "Yes" by the rules, but I wouldn't allow it in my game.
My reasoning for thinking it violates the intended spirit is that it approaches the 3.0 Haste level of "You're either foolish or reaching hard for some other build if you don't take this"-dom.
I think most fighters would benefit from Power Attack, but they don't all absolutely need it -- maybe they're duelists who go with Expertise or fast guys who are gunning for Spring Attack or specialists taking the Focus/Specialization/Improved Critical path.
But the only monk for whom Improved Natural Attack isn't a no-brainer as soon as the monk qualifies for it is a monk who isn't focused on melee combat of any kind -- which is an awfully big reach for a monk.
Hence my "Maybe". It seems like a clear-cut "Yes" by the rules, but I wouldn't allow it in my game.