I recently got my Chocobo to rank 5. For the longest time she had 24 minutes flat, now it's down to 22 minutes 30 seconds.

As for rank. I've watched my Chocobo fight mobs higher than us and I miss far more than she does. Rank 5, a milstone of the halfway mark to 10, gives us a 5% accuracy boost to all types. <..< I want something better and unique to each path.