Swashbuckler questions.

[Garion Beckett]

Hey guys. Ok got a weird question about a class feature.

Swashbuckler Weapon Training (Ex): At 5th level, a swashbuckler gains a +1 bonus on attack and damage rolls with one-handed or light piercing melee weapons. While wielding such a weapon, she gains the benefit of the Improved Critical feat. These attack and damage bonuses increase by 1 for every 4 levels beyond 5th (to a maximum of +4 at 17th level).

Now this says she gains the benefits of Improved Critical. Now in regard to feats and magic enchants, can she take keen or the feat Improved Critical?

[Imbicatus]

Any effects that increase threat range do not stack. She can take the feat or use a weapon with the keen enchantment, but the crit range is still only increased once.

[Azten]

She can, but they wouldn't stack.

[Statboy]

Paizo has been very careful to word keen, and improved critical to make sure that those kind of bonus's never stack. You can only double the threat range of a weapon once.